Ответ:

1)18-16y = -30y-10

-16y + 30y = -10 - 18

14y = -28

y = -2

2)5a -12 = -3(a-4)

5a-12= -3a+12

5a+3a = 12+12

8a = 24

a = 3

3)(x+5)(2x-20)=0

x+5=0 ; 2x-20=0

x=-5 ; 2x = 20

x = 10

4) (-3-9y)(2y+8)=0

-3-9y=0 ; 2y+8=0

-9y=3 2y=-8

y= -1/3 y= -4

5) (-0,3a + 2,7)(6a-36)(5a-25)=0

-0,3a+2,7=0 ; 6a-36=0 ; 5a-25=0

-0,3a= -2,7 ; 6a=36 ; 5a =25

a=9 ; a=6 ; a=5

6) x(x-5) =0

x=0 ; x-5=0

x=5