求未知数x: x-3/20x=18.7 1/4:1/8=x:1/10 1.5x-x=1 15x÷2=60

问题描述:

求未知数x:
x-
3
20
x
=18.7
1
4
1
8
=x:
1
10
1.5x-x=1 15x÷2=60

(1)x-

3
20
x=18.7
         
17
20
x=18.7
     
17
20
17
20
=18.7÷
17
20

             x=22;
(2)
1
4
1
8
=x:
1
10

      
1
8
x=
1
4
×
1
10

      
1
8
x=
1
40

   
1
8
1
8
=
1
40
÷
1
8

         x=
1
5

(3)1.5x-x=1
       0.5x=1
  0.5x÷0.5=1÷0.5
          x=2;
(4)15x÷2=60
  15x÷2×2=60×2
        15x=120
    15x÷15=120÷15
          x=8.