① 5x-20% x = 19.5 ② 2 (x-4) = 3 (X-12) ③3x-0.8×75%=2.1

① 5x-20% x = 19.5 ② 2 (x-4) = 3 (X-12) ③3x-0.8×75%=2.1

5x-20%x=19.5
4.8x=19.5
x=19.5÷4.8
x=4.0625
2(x-4)=3(x-12)
2x-8=3x-36
3x-2x=36-8
x=28
3x-0.8×75%=2.1
3x-0.6=2.1
3x=2.1+0.6
3x=2.7
x=2.7÷3
x=0.9