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

To find the age of the boy, we can set up a system of equations based on the given information and solve for the boy's age. By substituting values and simplifying, we find that the boy is 20 years old.

Step-by-step explanation:

To solve this problem, let's define the ages of the boy and his sister. Let's say the boy's age is B and the sister's age is S. We are given two pieces of information:

1. The age of the boy is twice that of his sister: B = 2S

2. Five years ago, the boy was 3 times the age of his sister: (B - 5) = 3(S - 5)

We can solve this system of equations to find the value of B. First, substitute the value of B from the first equation into the second equation:

(2S - 5) = 3(S - 5)

Now solve for S:

2S - 5 = 3S - 15

Simplify the equation:

S = 10

Now substitute the value of S back into the first equation to find B:

B = 2 * 10 = 20

Therefore, the boy is 20 years old.

Answer 2

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 * 10 \\ \: \: \: \: \: \: \: \: \: \: \: = 20`

hope this helps..

Good luck on your assignment..