1-0.75x=0.25
0.75x=1-0.25=0.75
x=1
9-3x=1.5x
9=4.5x
x=2
22X35+10x=1260
10x=1260-770=490
x=49
6x(1.5+x)=21.6
9x+6x^2=21.6
2x^2+3x-7.2=0
x=1.29或2.79