(1)68x+60x=256
128x=256
128x÷128=256÷128
x=2;
(2)8×(x+3.5)=100
8×(x+3.5)÷8=100÷8
x+3.5=12.5
x+3.5-3.5=12.5-3.5
x=9;
(3)3.2x-54=10
3.2x-54+54=10+54
3.2x=64
3.2x÷3.2=64÷3.2
x=20;
(4)4x+7.6×3=52.8
4x+22.8=52.8
4x+22.8-22.8=52.8-22.8
4x=30
4x÷4=30÷4
x=7.5.