解方程和简便计算

Question

如题所述

Answer 1

解方程：
(4/5)X-38=6 (1/2)X÷3=1.8
(4/5)X=6+38 * 0.5X=1.8×3*
( 4/5)X=44 0.5X=5.4
X=44÷(4/5)* X=5.4÷0.5*
X=44×(5/4) * X=10.8
X=55

8X=(6/25)÷(2/5) 1-(5/8)X=(8/9)×(3/8)
8X=(6/25)×(5/2)* 1-(5/8)X=1/3
8X=3/5X -(5/8)X=(1/3)-1*
X=(3/5)÷8 * -(5/8)X=-(2/3)
X=(3/5)×(1/8)* X=-(2/3)÷(-5/8)*
X=3/40 X=-(2/3)×(-8/5)*
X=16/15
简便计算：
(19/14)×49-(5/14)÷(1/49) [ 4-(1/15)×45]÷(1/2)
=(19/14)×49-(5/14)×49 = [4-3]×2
=[(19/14)-(5/14)]×49 =1×2
=1×49 =2
=49 (个人感觉这道题，按步骤算已经很简便了)

（熟练的话，用*标记的步骤可以省略）

有疑问，请追问

Answer 2

4x/5=44
4x=220
x=55

x/2=1.8*3=5.4
x=10.8

8x=3/5
x=3/40

1-5x/8=1/3
8-5x=8/3
8-8/3=5x
16/3=5x
x=16/15

=19X49/14-5X49/14
=(19-5)X49/14
=14X49/14
=49

=(4-3)X2
=2

Answer 3

55
10.8
3/40
16/15
49
2

Answer 4

求未知数解方程