ответ
5(1+х)-12=8
5-5х-12=8
5х=8-12+5
5х=1
х=1/5
х=0,2
Проверка
5*(0,2-1)+12=8
5*(-0,8)+12=8
-4+12=8
8=8
5(1 + х) - 12 = 8
5 + 5х - 12 = 8
5х - 7 = 8
5х = 8 + 7
5х = 15
х = 15 : 5
х = 3
проверка:
5(1 + 3) - 12 = 8
5 * 4 - 12 = 8
20 - 12 = 8
8 = 8
5(1+х)-12=8
5(1+х)=12+8
5(1+х)=20
5×1+5+х=20
5+5х=20
5х=20-5
5х=15
х=15÷5
х=3
