1.简便计算

题目

1.简便计算
16*2/3*(9*1/8) 1/4+5又2/7*1/4+3又5/7除4
8.8*12.5*100除4 4/9*[3/4-(7/16-0.25)]
求未知数x
(3+x)*0.4=30*4/25

答案

16*2/3*(9*1/8)
=(16*1/8)*(2/3*9)
=2*6
=12
1/4+5又2/7*1/4+3又5/7除4
=1/4+5又2/7*1/4+3又5/7乘以1/4
=1/4*(1+5又2/7+3又5/7)
=1/4*10
=5/2
8.8*12.5*100除4
=(8*12.5+0.8*12.5)*100除以4
=110*25
=2750
4/9*[3/4-(7/16-0.25)]
=4/9*(3/4+1/4-7/16)
=4/9*9/16
=1/4
(3+x)*0.4=30*4/25
1.2+0.4X=4.8
0.4X=3.6
X=9