Question

The cost of 2 pens and 2 pencils is Rs 18.
2 pens and 3 pencils cost Rs 20. What is the cost of a pen?​

Answer 1

Answer:

Step-by-step explanation:

2 pencils and 3 pens together cost Rs. 33 and 3 pencils and 2 pens together cost Rd. 27. What are the cost of one pencil and one pen?

Case 1

Let the cost of the pencil be- x

Let the cost of the pen be- y

Total cost- Rs.33

(Eq. 1.) 2x+3y=33

Case 2

Total cost= Rs.27

(Eq. 2.) 3x+2y=27

Therefore, from eq. 1 and 2,

2x+3y=33

3x+2y=27

By using elimination method

Multiply eq. 1 from 3 and eq. 2 from 2

6x+9y=99………. (Eq. 3)

6x+4y=54……….(Eq. 4)

By solving eq. 3 and 4, we get,

5y=45

y=9

By substituting the value of y in eq. 1

2x+3*9=33

2x+27=33

2x=6

x=3

Answer 2

Answer:

Solution:- (C) 15

Let the cost of pen and pencil be x and y

cost of 2 pens and one pencil is Rs. 35 (Given)

∴ 2x+y=35 ⟶eq  

n

(i)

cost of 3 pens and 4 pencils is Rs. 65

∴ 3x+4y=65 ⟶eq  

n

(ii)

Multiplying eq  

n

(i) by 4, we get

8x+4y=140 ⟶eq  

n

(iii)

Subtracting eq  

n

(ii) from (iii), we have

8x+4y−3x−4y=140−65

⇒ 5x=75

⇒ x=15

Hence, the cost of 1 pen is Rs. 15.