4x+0.5=7.5
4x=7.5-0.5
4x=7
x=7÷4
x=1.75
0.25x+3=0.3x
0.3x-0.25x=3
0.05x=3
x=3÷0.05
x=60
0.4(x-16 )=15.2
x-16=15.2÷0.4
x-16=38
x=38+16
x=54