(48:t+7)·6=90
48:t+7=90:6
48:t+7=15
48:t=15-7
48:t=8
t=48:8
t=6
Проверка:
(48:6+7)·6=90
(8+7)·6=90
15·6=90
90=90
100-(b·8-50)=30
b·8-50=100-30
b·8-50=70
b·8=70+50
b·8=120
b=120:8
b=15
Проверка:
100-(15·8-50)=30
100-(120-50)=30
100-70=30
30=30
9600:(540:d-4)=600
540:d-4=9600:600
540:d-4=16
540:d=16+4
540:d=20
d=540:20
d=27
Проверка:
9600:(540:27-4)=600
9600:(20-4)=600
9600:16=600
600=600