Question

100/9×8.1-81/10×91/9简便计算 。

2/3x-1/5x=4.9简便计算

Answer 1

100/9×8.1-81/10×91/9
=8.1×(100/9-91/9)
=8.1×1
=8.1
3/2x-1/5x=4.9
解：13/10x=4.9
x=4.9×10/13
x=49/13

追问

我说错了，第二个是2/3x-1/5x=4.9怎么算

追答

2/3x-1/5x=4.9
7/15x=4.9
x=4.9×15/7
x=10.5

Answer 2

100/9×8.1-81/10×91/9
=100/9*81/10-81/10*91/9
=81/10*(100/9-91/9)
=81/10*1
=8.1
2/3x-1/5x=4.9
10/15x-3/15x=49/10
7/15x=49/10
x=49/10*15/7
x=105/10
x=10.5

Answer 3

100/9×8.1-81/10×91/9
100/9×8.1-8.1×91/9
8.1(100/9-91/9)
8.1X1
8.1