1.2x％=13/40
2x/100=13/40
x/50=13/40
x=13/40÷1/50
x=16.25
2.3/4x-5x％=17.5
3/4x-5/100x=17.5
0.75x-0.05x=17.5
0.7x=17.5
x=17.5÷0.7
x=25