Question

Five years ago, Tom was one third as old as his father was then.In 5 years, Tom will be half as old as his father will be then. Find their ages now.Show your equation

Answer 1

The father is 35years old and the son Tom is 15years old

Explanation:

Let the father's be y

Let Tom's age be T

5 years ago:

The father's age is: y — 5

Tom's age:

T— 5.

But Tom's age was one third the father's age. This is written as:

T — 5 = 1/3(y — 5)

3(T — 5) = y — 5

3T — 15 = y — 5

3T — y = — 5 + 15

3T — y = 10 (1)

In 5years time:

The father's age is:

y + 5

Tom's age:

T + 5

But in 5years time, Tom will be half as old as his father. This is written as:

T + 5 = 1/2(y + 5)

2(T + 5) = y + 5

2T + 10 = y + 5

2T — y = 5 — 10

2T — y = — 5 (2)

Therefore, the equations are

3T — y = 10 (1)

2T — y = — 5. (2)

Solving by elimination method:

Subtract equation (2) from (1)

3T — y = 10

— (2T — y = — 5)

T = 15

Substituting the value of T into equation (1)

3T — y = 10

3(15) — y = 10

45 — y = 10

45 — 10 = y

y = 35

Therefore,

The father is 35years old and the son Tom is 15years old