Question

Alex is three times as old as Rita. Three years later, Alex will be two times as old as Rita. Alex's present age is years.

Answer 1

Let Rita's present age $=x$ years.
Accordingly, Alex's present age $=3x$ years.

Rita's age after 3 years $=x+3$
Alex's age after $3$ years $=3x+3$
Given that $3$ years later, Alex will be two times as old as Rita.
$\Rightarrow 3x+3=2(x+3)$
$\Rightarrow 3x+3=2x+6$
Step 1: Subtract $2x$ from both the sides of the equation
$\Rightarrow 3x+3-2x=2x+6-2x$
$\Rightarrow x+3=6$
Step 2: Subtract $3$ from both the sides of the equation
$\Rightarrow x+3-3=6-3$
$\Rightarrow x=3$
Rita's present age is $3$ years
Alex's present age is $3x=3\times 3=9$ years