1)
5x-3×1/2=4×2/3
5x=4×2/3+3×1/2
5x=4×4/6+3×3/6
5x=8×1/6
x=4/15
2)
18-2x=16×3/4
-2x=16×3/4-18
-2x=16×3/4-17×4/4
-2x=-1×1/4
2x=1×1/4
2x=5/4
x=5/2
3)
(x-5×7/12):25=7/75
(x-35/12)×1/25=7/75
12x-35/12×1/25=7/75
12x-35/300=7/75
75(12x-35)=2100
12x-35=28
12x=28+35
12x=63
x=5×1/4