20-4x=5
4x=20-5,
4x=15
x=3.75;
3
5 :
7
12 =
9
10 :x
3
5 x=
7
12 ×
9
10 ,
x=
7
12 ×
9
10 ÷
3
5 ,
x=
7
12 ×
9
10 ×
5
3 ,
x=
7
8 ;
1
2 ×
1
3 +75%x=
1
4 .
1
6 +
3
4 x=
1
4 ,
3
4 x=
1
4 -
1
6 ,
3
4 x=
1
12 ,
x=
1
12 ÷
3
4 ,
x=
1
12 ×
4
3
x=
1
9 .
20-4x=5
4x=20-5,
4x=15
x=3.75;
3
5 :
7
12 =
9
10 :x
3
5 x=
7
12 ×
9
10 ,
x=
7
12 ×
9
10 ÷
3
5 ,
x=
7
12 ×
9
10 ×
5
3 ,
x=
7
8 ;
1
2 ×
1
3 +75%x=
1
4 .
1
6 +
3
4 x=
1
4 ,
3
4 x=
1
4 -
1
6 ,
3
4 x=
1
12 ,
x=
1
12 ÷
3
4 ,
x=
1
12 ×
4
3
x=
1
9 .