1 8 + 3 8 = 3 10 + 9 10 = 7 16 - 3 16 = 1- 5 18 = 19 12 -1=

1
8 +
3
8 =
1
2
3
10 +
9
10 =1
1
5
7
16 -
3
16 =
1
4 1-
5
18 =
13
18

19
12 -1=
7
12
17
20 +
7
20 =1
1
5
5
6 +（
1
6 +
1
6 ）=1
1
3
17
30 +
23
30 -
7
30 =1
1
10
1-（
2
9 +
4
9 ）=
1
3 1-
5
12 +
11
12 =1
1
2