Question

Ben is 20 years older than Daniel. Ben and Daniel first met two years ago. Three years ago, Ben was 3 times as old as Daniel.How old is Ben now?

Answer 1

Let $b=$ Ben's age
Let $d=$ Daniel's age

We know:
$b=d+20$
and
$b-3=3(d-3)$

Plug the value of $b$ into the second equation:
$(d+20)-3=3(d-3)$
$\rightarrow d+17=3d-9$
$\rightarrow-2d+17=-9$
$\rightarrow-2d=-26$
$\rightarrow d=13$

Since Ben is 20 years older than Daniel, Ben is 13+20=33 years old.