1000 - (42x - 13x) = 131000 - 42x + 13x = 131000 - 29x = 13-29x = 130 - 100-29x = -87x = -870 / -2x = 30
Ответ: x = 30.
1000 - (42x - 13x) = 13
1000 - 42x + 13x = 13
1000 - 29x = 13
-29x = 130 - 100
-29x = -87
x = -870 / -2
x = 30
Ответ: x = 30.