Question

Five years hence a man’s age will be three times his son’s age. If the man's age is represented by 'x' and his son's age by 'y', which among the following options is a linear equation in two variables representing this statement?

• A. x - 3y = 10
• B. x - 3y = 12
• C. x + 3y = 12
• D. x + 3y = 10

Answer 1

The correct option is A x - 3y = 10

Let the present age of the man and his son be x years and y years respectively.

Five years hence,
Man's age = (x + 5) years
Son's age = (y + 5) years

According to the question, we have
$x+5=3(y+5)\Rightarrow x+5=3y+15\Rightarrow x-3y=10$
This is a linear equation in two variables which represents the given statement.