题目

算一算。 18+3=                  40+20=                70-50= 96-90=                 31+13=                85-5= 18+42=                 78-7=                 30+70= 答案：解： 18+3=21                  40+20=60                70-50=20 96-90=6                   31+13=44                85-5=80 18+42=60                 78-7=71                 30+70=100                   

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