Question

what'll be number added to the numerator and denominator of a fraction 5 /7 make equal to 20 / 21 ​

Answer 1

Answer:-

Let the number to be added be x.

Then, initial fraction = 5/7

And, after adding x to numerator and denominator, we get, final fraction = (5 + x)/(7 + x)

Now, according to the question, this final fraction is equal to 20/21

So,

(5 + x)/(7 + x) = 20/21

On cross multiplying, we get,

→ 21(5 + x) = 20(7 + x)

→ 105 + 21x = 140 + 20x

→ 21x - 20x = 140 - 105

→ x = 35 Ans

Verification:-

We have to verify whether (5 + x)/(7 + x) = 20/21 at x = 35

Considering LHS:

(5 + x)/(7 + x)

at x = 35,

= (5 + 35)/(7 + 35)

= 40/42

= 20/21

Considering RHS:

20/21

So LHS = RHS

Hence verified!