4920*24-17x12
=118080-204
=117876
4/7*（13/14+15/16*7/8）
=4/7x(13/14+105/128)
=4/7x(832/896+735/896)
=4/7x1567/224
=1567/1568
（4/7-5/14）*（1/2+1/4）
=3/14x3/4
=9/56
（3/8+1/27）x8+19/27
=(81/216+8/216)*8+19/27
=89/216*8+19/27
=89/27+19/27
=4
12.75-（0.375+0.75）
=12.75-0.75-0.375
=12-0.375
=11.625
（6/7*125）x7x8
=(6/7*7)*(125*8)
=6*1000
=6000
1*[(1/3-1/5)x3/8]
=1*[1/3*3/8-1/5*3/80]
=1*[1/8-3/40]
=1*1/20
=1/20
16/17*8+1/17x1/8
=128/17+1/136
=1024/136
=7又73/136
直接写得数
0.3*3/5=0.18
5-5/12=4又7/12
3.7+5= 8.7
300x0.3％=0.9
5/144x12=5/12
4/15x1/4=1/15
（4.2+3/4）x2x0=0
3x11/2+3x1/2=18
解方程
6x-7=2x+1
6x-2x=7+1
4x=8
x=8/4
x=2
8*(15*x)=1
x=15*8
x=120
x=1/120
4/5x(x+3)=4.2
x+3=4.2除4/5
x+3=5.25
x=2.25
(x+16)x2=76
x+16=76/2
x+16=38
x=38-16
x=22
500x乘3/4*25=30
500x=30/18.75
500x=1.6
x=14.6/500
x=0.0032
81x-342=76乘(x-2)
解: 81x-342=76x-152
81x-76x=342-152
5x=190
x=38
6x+9乘2.5=32.7
6x=32.7-22.5
6x=10.2
x=10.2/6
x=1.7
9.72-x=1 1/6+0.9
x=11/6+9/10
x=41/15
x=9.72-41/15
x=6又74/75
算完了.