# Age, Ratio word problem

A is x years old. In 4 years time his brother B will be 3 times as old as him. Find the age of B in 4 years time.

• What have you tried? See also this ratio problem. – Dietrich Burde Dec 2 '18 at 19:15
• I have tried various approaches. But my teacher restricted me to solve it by algebra. – Wardah Dec 2 '18 at 19:18

$$x$$ is A's age and let's call B's age $$y$$ at this point in time
Hint : In 4 years time A: is $$x+4$$ years old and B is $$y+4$$ years old
We know that B will be 3 times older than A in 4 years, aka $$3*(x+4)=y+4$$
Solving for $$y$$ : $$y=3x+8$$
In four years time B will be $$y+4$$ years old or aka $$3x+8+4 = 3x+12$$