Question

Уравнения 99 баллов!!!!

1) -2x=-4
2) -2/5y=3/10
3) -5y+7=42
4) 8y-(7y-142)=51
5) (6y+1)-(3-2y)=14

Answer 1

1)
-2x=-4
x=4/2
x=2
2)
-2/5y=3/10
-2/5y=0,3
-y=5/2*0,3
-y=5/2*3/10
-y=1/2*1/3
-y=3/4
y=-3/4
3)
-5y+7=42
-5y=42-7
-5y=35
y=-7
4)
8y-(7y-142)=52
8y-7y+142=52
y+142=52
y=51-142
y=-91
5)
(6y+1)-(3-2y)=14
6y+1-3+2y=14
8y-2=14
8y=14+2
8y=16
y=2