99十18=100一1十18=117
47十33=47十30十3=81
87一49=87一(50一1)=87一50十1=38
125一26=125一(25十1)=125一25一1=99
1. 7 + 8 = 15
2. 12 - 5 = 7
3. 6 + 9 = 15
4. 15 - 6 = 9
5
6 + 9 = 15
7 + 8 = 15
8 = 15
9 = 15
10 = 14
99十18=100一1十18=117
47十33=47十30十3=81
87一49=87一(50一1)=87一50十1=38
125一26=125一(25十1)=125一25一1=99
1. 7 + 8 = 15
2. 12 - 5 = 7
3. 6 + 9 = 15
4. 15 - 6 = 9
5
6 + 9 = 15
7 + 8 = 15
8 = 15
9 = 15
10 = 14