1) a-b-20=40, a-b=40+20, a-b=60, a=60+b
(a+b):5=10, a+b=10*5, a+b=50
a=60+b
a+b=50 ⇒ 60+b+b=50
60+2b=50
2b=50-60
2b=-10
b=-10:2
b=-5
a=60+(-5)
a=55
cele 2 numere sunt 55 si -5
2)i+u+c=160
c=2i
u=2c+3i, u=2*2i+3i, u=4i+3i, u=7i
i+2i+7i=160
10i=160
i=160:10
i=16
c=2i, c=16*2, c= 32
u=2c+3i, u=32*2+16*3, u=64+48, u=112
Iepurasul costa 16 lei, catelul costa 32 lei si ursuletul costa 112 lei