4x+0.5×3=6.7
4x+1.5=6.7
4x=5.2
x=1.3
5x-3.3=7.3
5x=10.6
x=2.12
1.7-0.7x=20
0.7x=-18.3
x≈-26.14
x-4.5+5.5=15
x+1=15
x=14