Răspuns:
s) (72+s-56)-(30-10+5)=25
(72+s-56)-25=25
metoda mersului invers => 72+s-56=25+25
72+s-56=50
72+s=50+56
72+s=106
s=106-72
s=34
t) (36-30-t)+72-70=28:7
(6-t) + 72-70=4
metoda mersului invers => 6-t= 4-2
6-t=2
t=6-2
t=4
u) (49-36+u)-8-20=9
metoda mersului invers => 13+u=9+8+20
13+u=37
u=37-13
u=24
v) (v-25-16)+30-50=3
metoda mersului invers => v-25-16=3+50-30
v-25-16=23
v=23+16+25
v=64
