口算算术1.90-9= 24-10-7=46+5= 20+13-9=8+57= 34+(25+5)=98-70= 58-(58-8)=65+20= 39+7-20=2.25+7= 50-8= 86-5= 4+65=20+67= 42+30=73-40= 85-7=8+45= 76-60=

1. 90-9= 81 24-10-7=7
46+5= 51 20+13-9=22
8+57= 65 34+(25+5)=64
98-70= 28 58-(58-8)=8
65+20= 85 39+7-20=26
2. 25+7=35 50-8= 42
86-5= 81 4+65=69
20+67= 87 42+30=72
73-40= 85-7=
8+45= 76-60=

= =|||1. 90-9=81 24-10-7=7 46+5=51 20+13-9=24 8+57=65 34+(25+5)=64 98-70=28 58-(58-8)=8 65+20=85 39+7-20=262. 25+7=32 50-8=...