13 |
20 |
2x+0.7=9,
2x+0.7-0.7=9-0.7,
2x=8.3,
2x÷2=8.3÷2,
x=4.15;
(2)x:
7 |
10 |
x×
10 |
7 |
10 |
7 |
3 |
10 |
100 |
70 |
21 |
70 |
21 |
70 |
21 |
70 |
79 |
70 |
79 |
70 |
70 |
79 |
70 |
79 |
x=
840 |
79 |
x=10
50 |
79 |
13 |
20 |
7 |
10 |
13 |
20 |
7 |
10 |
10 |
7 |
10 |
7 |
3 |
10 |
100 |
70 |
21 |
70 |
21 |
70 |
21 |
70 |
79 |
70 |
79 |
70 |
70 |
79 |
70 |
79 |
840 |
79 |
50 |
79 |