Question

решить уравнение
90:а+12=42

Answer 1

90/a + 12 = 4290/a = 42 - 12
90/a = 30 | * a
90 = 30*a | : 30
a = 3

Answer 2

90 = 30*a | : a

Answer 3

???

Answer 4

объясни

Answer 5

опечатка, 30