求未知数. 33/5:5.4=1.5:x 8.2x-60=4.2x+20 3x-10(10-x)=17.
问题描述:
求未知数.
3
:5.4=1.5:x 3 5
8.2x-60=4.2x+20
3x-10(10-x)=17.
答
(1)3
:5.4=1.5:x3 5
3
x=5.4×1.53 5
3
x÷33 5
=8.1÷33 5
3 5
x=2.25
(2)8.2x-60=4.2x+20
8.2x-60-4.2x=4.2x+20-4.2x
4x-60=20
4x-60+60=20+60
4x=80
4x÷4=80÷4
x=20;
(3)3x-10(10-x)=17
13x-100=17
13x-100+100=17+100
13x=117
13x÷13=117÷13
x=9.