2/3X-13/30=1/5X
(2/3+1/5)x=13/30
13/15x=13/30
x=1/2
X/25=1.2/75
x=25*1.2/75=1.2*25/75=1.2/3=0.4
5+1/4-X=3
x=5+1/4-3=2+1/4=9/4
6X+0.5×7=6.5
6x+3.5=6.5
6x=6.5-3.5
6x=3
x=0.5
2.5/X=7.5/12
1/x=3/12
x=12/3
x=4
2÷[（5/6-2/9）×1/11]
=2÷[（45/54-12/54）×1/11]
=2÷[（11/18）×1/11]
=2÷[1/18]
=2×18
=36
7.25×7.3-3.3×7.25
=7.25*(7.3-3.3)
=7.25*4
=7*4+0.25*4
=28+1
=29
220÷[56×（3/7-3/8）]
=220÷(56×3/7-56×3/8）
=220÷(24-21)
=220÷3
=220/3
（1/3+1/4-1/6）×24
=1/3×24+1/4×24-1/6×24
=8+6-4
=10