Question

Shekhar has 12 maths books. 40% of the total books Shekhar has are maths books. How many books does Shekhar have​

Answer 1

Answer:

ANSWER:

Let her monthly income be Rs x.

Savings = Rs 120

Expenditure = 90% of x=90100x=9x10

Savings = Total monthly salary − Expenditure = x−9x10=x10 = 120

x=10×120=1200

Thus, total monthly salary = Rs 1200

Answer 2

➤ Given :-

Total number of Maths books :- 12

Percentage of Maths books :- 40%

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➤ To Find :-

Total number of books with Shekhar...

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★ How to do :-

Here, we are given with the total number of books with Shekhar that are maths. We are also given with the percentage value of those maths books with total number of books. We are asked to find the total number of books that Shekhar is having totally. To find the answer of this question, we use an other concept which is used to find the total amount of anything when we are given with part of it and the percentage value of it. We are also given with the same. So, we can use the same method to find our answer. We also use the variables in this answer, so that we can find the value of that variable by an other method called as the transposition method. We can also check our answer that whether it's correct or not. This method will be done at last as the verification method. So, let's!!

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➤ Solution :-

${\sf \leadsto 40\% \: of \: y = 12}$

Write the percentage as fraction and 'of' as multiplication.

${\sf \leadsto \dfrac{40}{100} \times y = 12}$

Shift the number 12 from RHS to LHS.

${\sf \leadsto y = \dfrac{12 \times 100}{40}}$

Write the fraction in lowest form by cancellation method.

${\sf \leadsto y = \dfrac{12 \times \cancel{100}}{\cancel{40}} = \dfrac{12 \times 5}{2}}$

Multiply the remaining numbers.

${\sf \leadsto y = \dfrac{60}{2}}$

Simplify the fraction to get the answer.

${\sf \leadsto y = 30}$

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${\red{\underline{\boxed{\bf So, \: the \: total \: number \: of \: books \: is \: 30.}}}}$

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Verification :-

${\sf \leadsto 40\% \: of \: y = 12}$

Substitute the value of y.

${\sf \leadsto 40\% \: of \: 30 = 12}$

Write the percentage as fraction and 'of' as multiplication sign.

${\sf \leadsto \dfrac{40}{100} \times 30 = 12}$

Write the fraction in lowest form on LHS.

${\sf \leadsto \cancel \dfrac{40}{100} \times 30 = 12}$

Write the obtaining fraction.

${\sf \leadsto \dfrac{2}{5} \times 30 = 12}$

Write both numerators with a common denominator.

${\sf \leadsto \dfrac{2 \times 30}{5} = 12}$

Multiply the numbers.

${\sf \leadsto \dfrac{60}{5} = 12}$

Simplify the fraction on LHS.

${\sf \leadsto 12 = 12}$

So,

${\sf \leadsto LHS = RHS}$

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Hence verified !!