Explicație pas cu pas:
1. 143:13=11 ( nu are rest)
2.8×7+3=59
3. a) 1+0+1+64-45=66-45=21
b)9×8+1×144-150=72+144-150=216-150=66
4.a:3=12
a=12×3=36
a:2=18 ore
5. 7 sec.................203 m
4 sec...................a m
a=203×4/7=812/7=116
6. 1,2, 4, 5, 8, 10, 20
7. 1221, 1230, 1242, 1251, 1254, 1263, 1272, 1275, 1281, 1284, 1287, 1290, 1293, 1296
