Răspuns:
3. a) -x+21=7, x=14
-14+21=7
7=7 (A)
b) 11-x=2, x=9
11-9=2
20=2 (A)
c) 3x-35=1, x=-12
3·(-12)-35=1
-36-35=1
-71=1 (F)
d) x:2=9, x=18
18:2=9
9=9 (A)
e) -16:x=-2, x=-8
-16:(-8)=-2
2=-2 (F)
