Question

The age of a boy is twice that of his sister. five years ago the boy was 3 times the age of his sister. How old is the boy

Answer 1

Answer:

20 years old.

Solution,

Let the age of sister be X

Let the age of boy be 2x

Now,

Five years ago,

$3(x - 5) = 2x - 5 \\ or \: 3x - 15 = 2x - 5 \\ or \: 3x - 2x = - 5 + 15 \\ x = 10$

Again,

Replacing value,

$age \: of \: boy = 2x \\ \: \: \: \: \: \: \: \: \: \: \: \: \: = 2 \times 10 \\ \: \: \: \: \: \: \: \: \: \: \: = 20$

hope this helps..

Good luck on your assignment..