Question

A man is twice as old as his son today.ten year ago he was thrice as old as the son.what will be the man age today?
30
60
20
40

Answer 1

40 is the right answer.

CONSIDER:

• Let the man's present age be x
• Let the son's present age be y
• The age of the man before 10 years be x -10
• The age of son before 10 years be y - 10

GIVEN:

• Man is twice as old as his son today.
• x = 2y

• Ten years ago the man was thrice as old as the son.
• x - 10 = 3 (y - 10)

TO FIND:

The present age of man, x

SOLUTION:

Substitute x = 2y in x - 10 = 3 (y - 10)

$2y - 10 = 3(y - 10) \\ \\ 2y - 10 = 3y - 30 \\ \\ - 10 + 30 = 3y - 2y \\ \\ 20 = 3y - 2y \\ \\ y = 20$

Present age of son is 20.

Substitute y = 20 in x = 2y

$x = 2y \\ \\ x = 2 \times 20 \\ \\ x = 40$

ANSWER:

• The present age of the man is 40.

• The man is 40 years old now.

• The present age of son is 20.

• Ten years ago , the age of man is 40 - 10 = 30

• The age of son before ten years is 20 - 10 = 10