Question

a+b=45,a:b=5 rest 3, a,b = ?

Answer 1

a+b=45 
a:b=5 r=3 => a=b*5+3
Inlocuim:
b*5+3+b=45 => 6b=42 => b=7
                     a=7*5+3=35+3=38
Proba: 7+ 38=45 Adevarat.

Answer 2

A=5b + 3
A + B= 5b + 3 +b
A + B= 6b + 3
45= 6b + 3
6b= 45-3
6b= 42
B= 42:6
B=7

A=6b+3=5x7+3
=35+3
=38