tatsach ...............................

Andrey1977 а) 3(a – 5) – 2(а – 4) = 8;

3a-15-2a+8=8
a-7=8
a=8+7
a=15

б) −5(4,2у+1) + 4(1,4у−2)= −20,7

-21y-5+5.6y-8=-20,7
-15.4y-13=-20.7
-15.4y=-20.7+13
-15.4y=-7.7
y=-7.7:-15,4
y=0.5