Bjørn is 3 years older than Icar was 5 years ago. If the sum of their ages now is 66, how is each person?

You use process of substitution so you need two equations:

1.)x+y=66

2.) Bjorn(x)=(y-5)+3 (Icar represents y, and Bjørn represents x if you didn't catch that.)


Plug (y-5)+3 in for X:
((y-5)+3)+y=66
y-5+3+y=66
y-2+y=66
2y-2=66
2y=68
y=34

Plug 34 for in for Y to get X:
(34-5)+3=32

Icar is 34
Bjørn is 32