2(3x+15)-2x=76
6x+30-2x=76
4x=46
x=23/2
12x+2=2.8×5+8x
4x=16
x=4
2x+x除以2=22.5
2.5x=22.5
x=9
3x+4.5=7x-11.5
-4x=-16
x=4 2(3x+15)-2x=76
6x+60-2x=76
4x=16
x=4
12x+2=2.8×5+8x
12x-8x=17-2
6x=15
x=2.5
2x+x除以2=22.5
4x+x=45
5x=45
x=9
3x+4.5=7x-11.5
3x-7x=-11.5-4.5
-4x=-16
x=4