19-4=
67-7=
5+50=
88-8=
18-9=
70+8=
87-80=
49-40=
13-6=
56-50=
60+7=
4+30=
71-6= 35-10= 30-6= 13-7+40=
34-4= 60+18= 32+8= 67-40+5=
25+7= 87-6= 2+54= 10+6+8=
问题:
解答: