Ex. 4: 1. 13h -10min.=12h, 50min. (12:50)-ajunge la bunica
2. 12h 50min,-30min.=12h 20min. (12:20)-pleaca de la bunica
3. 12h-20min.=12h (12:00)- ajunge acasa
Ex. 6: a) ( x + 20 ) : 12 + 68 = 78
( x + 20 ) : 12 = 78 - 68
( x + 20 ) : 12 = 10
x + 20 = 10 × 12
x + 20 = 120
x = 120 - 20
x = 100
b) (x+282-75):2=104
x+282-75=104x2
x+282-75=208
x+282=208+75
x+282=283
x=283-282
x=1
c) x×4:10=133-101
x×4:10=32
x×4=32×10
x×4=320
x=320:4
x=80
c) 101-(101-102:x)=202:101
101-(101-102:x)=2
101-102:x=101-2
101-102:x=99
102:x=101-99
102:x=2
x=102:2
x=51
d) (x+112):5+113=369-134
(x+112):5+113=235
(x+112):5=235-113
(x+112):5=122
x+112=122×5
x+112=610
x=610-112
x=498
e) (x-3×8)×2:8=104:13
(x-24)×2:8=8
(x-24)×2=8×8
(x-24)×2=64
x-24=64:2
x-24=32
x=32+24
x=56
