四年级递等式计算150道 速度因为是暑假作业~

（720+270）÷55-120÷24
=990÷55-120÷(12×2)
=990÷110×2-120÷12÷2
=9×2-10÷2
=18-5
=13

（63+480÷16）-29
=（63+30×16÷16）-29
=63+30-30+1
=64

13.67-2.97+25.8
=13.67-3+0.03+25.8
=10.67+0.03+25.8
=10.7+25.8
=36.5

7.06-2.78+13.78
=7.06+13.78-2.78
=7.06-（13.78-2.78）
=7.06+11
=18.06

0.64×25×7.8+2.2
=0.16*4*25*7.8+2.2
=0.16*100*7.8+2.2
=16*7.8+2.2
=127

2÷2.5+2.5÷2
=4/5+5/4
=2.05

194－64.8÷1.8×0.9
=194-36*0.9
=194-32.4
=161.6

36.72÷4.25×9.9
=8.64*9.9
=85.536

5180－705×6
=5180-4230
=950

24÷2.4－2.5×0.8
=10-2
=8

(4121+2389)÷7
=6510/7
=930

671×15-974
=10065-974
=9091

469×12+1492
=5628+1492
=7120

405×(3213-3189)
=405*24
=9720

1）、0.36x1.5x0.4=0.4x5x0.36x0.3=2