Question

three books and a pen cost is Rs 70 and 2 pen and a book cost Rs 40 how much wil a book and a pen cost is ?​

Answer 1

A n s w e r

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G i v e n

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• 3 books and a pen cost is Rs 70

• 2 pen and a book cost Rs 40

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F i n d

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• Cost of a book

• Cost of a pen

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S o l u t i o n

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• Let the cost of 1 book is "b"

• Let the cost of 1 pen is "p"

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$\underline{\bold{\texttt{Cost of 3 books :}}}$

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➠ 3b

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$\underline{\bold{\texttt{Cost of 1 pen :}}}$

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➠ 1p

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Given that the cost of 3 books and 1 pen cost is Rs 70

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So ,

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➜ 3b + 1p = 70 ⚊⚊⚊⚊ ⓵

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$\underline{\bold{\texttt{Cost of 1 book :}}}$

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➠ 1b

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$\underline{\bold{\texttt{Cost of 2 pens :}}}$

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➠ 2p

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Given that , 2 pen and a book cost Rs 40

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So,

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➜ 1b + 2p = 40 ⚊⚊⚊⚊ ⓶

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⟮ Multiplying equation ⓵ with 2 ⟯

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➜ 2(3b + 1p) = 2(70)

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➜ 6b + 2p = 140 ⚊⚊⚊⚊ ⓷

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⟮ Equation ⓷ - ⓶ ⟯

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➜ 6b + 2p -(1b + 2p) = 140 - 40

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➜ 6b + 2p - b - 2p = 100

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➜ 5b = 100

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➨ b = 20 ⚊⚊⚊⚊ ⓸

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• Hence the cost of 1 book is Rs 20

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⟮ Putting b = 20 from ⓸ to ⓵ ⟯

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➜ 3(20) + 1p = 70

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➜ 60 + p = 70

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➜ p = 70 - 60

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➨ p = 10

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• Hence the cost of 1 pen is Rs 10

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$\underline{\bold{\texttt{Cost of 1 book and 1 pen :}}}$

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➜ 20 + 10

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➨ 30

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• Hence the cost of 1 book and 1 pen together is Rs 30

Answer 2

Answer:

The cost of 1 book and 1 pen together is Rs 30.

Step-by-step explanation:

• We are given that, 3 books and a pen cost is Rs 70 and 2 pen and a book cost Rs 40.
• We have to find that, what is cost of a single book and cost of single pen.
• For solving this question, let us consider- cost of 1 book is "b" and cost of 1 pen be "p".
• So according to above consideration-

Cost of 3 books will be $3b$ and cost of 1 pen will be $1p$.

So according to given, that- cost of 3 books and 1 pen is Rs 70.

So,

$3b+1p=70$ let this be equation 1.

Cost of 1 book is $1b$ and cost of 2 pens is$2p$.

So, according to given condition of- 2 pen and a book is Rs 40.

$1b+2p=40$ let this be equation 2.

Now multiplying equation 1 with equation 2, we get-

$2(3b+1p)=2(70)\\6b+2p= 140$let this be equation 3.

Now subtracting equation 3 from equation 2.

we get- $6b+2p-(1b+2p)140-40\\6b+2p-b-2p=100\\5b=100\\b=20$

So we get the cost of 1 book is Rs 20.

Now putting the value of b in equation 1.

$3(20)+1p=70\\60+p=70\\p=70-60\\p=10$

So the value of 1 pen is Rs 10.

now the value of 1 book and 1 pen is

$20+10\\30$

Hence, the cost of 1 book and 1 pen together is Rs 30.

#SPJ2

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