(10X一90十2X)÷2=75
(12X一90)÷2=75
12×-90=150
12×=240
×=20
解:(10X一90十2X)÷2=75
两边同乘以2,得
10X一90十2X=150
两边同加90,得
10X十2X=240
12x=240
x=20
10x-90+2x=150
10x+2x=240
12x=240
x=20
求采纳
解:
10x+13y=580
10x=580-13y
x=58+1.3y
13y=580-10x
y=13分之580-13分之10x
(12X-90)➗2=75
6X-45=75
6X=120
x=20