(共15张PPT)
60-20=
77
1+20=
21
40+8=
48
10+30=
40
70+7=
40
70-40=
30
50-20=
30
50+20=
70
12
+30=
40+20=60
60+2=62
30+20=50
50+4=54
50+40=90
90+3=93
60+10=70
70+2=72
50-40=10
10+3=13
70-50=20
20+7=27
80-80=0
0+3=3
12
+30=
40+2=42
42
60+2=62
独立练习
21+30=
65-40=
55-20=
55+20=
70+12=
72-10=
89-80=
17+30+20=
20+8=28