12(x - 8)=132
12x-96 = 132
12x = 132 - 96
12x = 36
x = 36/12
x = 3
84/x+5=17
84/x=17-5
84/x=12 | *x
84*x/x
84=12*x
12*x=84
x=84/12
x=7
320/(8x-40)=10
8x-40=320:10
8x-40=32
8x=40+32
8x=72
x=72:8
x=9
90(x-8)+60=510
90x-720+60=510
90x=720-60+510
90x=1170
x=1170/90
x=13
1826-12x=1562
1826-1562=12x
264=12x
x=264/12
x=22