Question

If b is a number obtained by first dividing 63 by 7, then adding 2, and multiplying
the sum by 2, what is b?

Answer 1

Answer:

Let the tenth's digit be x and one's digit be y.

Then the number is 10x+y.

By the first condition-

(x+y)×8−5=10x+y

⇒2x−7y=−5 ..(i)

By the second condition-

(x−y)×16+3=10x+y

⇒6x−17y=−3 ..ii)

Multiplying (i) by 3, we get

6x−21y=−15 ..(iii)

Subtracting (ii) from (iii), we get

−4y=−12

⇒y=3.

Substituting y=3 in (i)

2x−7×3=−5

⇒x=8

∴ The number is 10×8+3=83.