2、 105、 18、960、2 1

3, (48- 12)÷9=4

4、88、99、29、64、 136、 136

5, (25+28+3 1+20)÷4=26

6, 72÷2=36 kg 180÷36=5 or 180÷(72÷2)=5.

7.25× 8 = 20018× 8 =144 200+144 = 344 kg or 25×8+ 18×8=344 or (25+18

8、36、7、 156、 1 1

9、6×3+2+4 6×2+4×3 6×4×(3-2) 3×(6+4-2) 3×(6+4÷2)(6-3)×(4×2)

10, (1) Scheme I150× 6+60× 4 =140 Scheme II100×10 =/kloc-.

(2) Scheme I 150×4+60×6=960 Scheme II100×/kloc-0 =1000, Scheme F is economical.

1 1、①× ②√ ③√ ④×

12, the first two months: 138-48=90 yuan per month: 138÷3=46 yuan.

13， 124÷2 = 62cm 62 x3 = 186cm

14, (1)(△-□)× (blue△+red□) = ◇ (2) (△×□)-(blue△ red□) =1

15, the password is 9898.