Răspuns:
ex 5
x+y+z=45
x=28
z=x/4
z=28÷4=7
28+y+7=45
y+35=45
y=45-35=10
ex 6
(9×4)÷c=6
36/c=6
6c=36
c=36/6=6
ex 7
3b/3=9
b=9
