12.
a - primul numar
b - al doilea numar
a+b=140
[tex]\frac{a}{4}[/tex] = [tex]\frac{b}{3}[/tex] => a=[tex]\frac{4*b}{3}[/tex] inlocuim in prima relatie =>
7*b = 3*140
b=[tex]\frac{3*140}{7}[/tex] = 3 * 20 = 60
a = 140 - 60 = 80
13.
a/2 + 15 = 55
a/2 = 55 - 15
a/2 = 40
a = 2*40
a=80
