Пошаговое объяснение:
a) 98- ((45+x) - 38 )= 42
(45 + x) - 38 = 98 - 42
45 + x - 38 = 56
7 + x = 56
x = 56 - 7
x = 49
б) 25*(328-8*x)= 5400
328 - 8x = 5400:25
328 - 8x = 216
8x = 328 - 216
8x = 112
x = 112 : 8
x = 14
