1. 我会算。

13-9=            16-7=            12-6=            11-8=            17-9=

15-8=            16-9=            14-8=            15-6=            11-7=

18-9=            14-7=            12-9=            13-3=            11-2=

11-3=            12-8=            11-4=            15-9=            17-8=