Răspuns:
75.
(216×3-321×2)+18:x=9
(648-642)+18:x=9
6+18:x=9
18:x=9-6=3
18=3x
x=18:3
x=6
76.
(x-21:3+7×5):6=10
x-7+35=10×6=60
x-7=60-35=25
x=25+7
x=32
77.
(11-x:5+6×4):4=8
11-x:5+24=8×4=32
11-x:5=32-24=8
-x:5=8-11=-3
-x=-3×5=-15
x=15
78.
(51-36:x+9×3):8=9
51-36:x+27=9×8=72
51-36:x=72-27=45
-36:x=45-51=6
-36=6x
6x=36
x=36:6
79.
(23-42:7+y×7):9=5
23-6+7y=5×9=45
-6+7y=45-23=22
7y=22+6=28
y=28:7
y=4
Explicație pas cu pas:
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