我要10道递等式计算题...0.64×25×7.8+2.2 2÷2.5+2.5÷2 194－64.8÷1.8×0.9 36.72÷4.25×9.9 5180－705×6 24÷2.4－2.5×0.8 (4121+2389)÷7 671×15-974 469×12+1492 405×(3213-3189)

1、0.64*25*7.8+2.2
=4*25*.16*7.8+2.2
=100*.16*7.8+2.2
=16*7.8+2.2
=124.8+2.2
127
2、2/2.5+2.5/2
=.8+1.25
=2.05
3、

1.原式=16/25*25*39/5+2.2
=16*39/5+2.2
=127
2.原式=2÷5/2+5/2*1/2
=4/5+5/4
=0.8+1.25
=2.05
3.原式=194-64.8÷(1.8÷0.9)
=194-32.4
=161.6
4.原式=36.72÷17/4*9.9
=36.72*4/17*9.9
=8.64*9.9
=85.536
5.原式=5180-4230
=950
6.原式=10-2
=8
7.原式=6510÷7
=930
8.原式=10065-974
=9091
9.原式=5628+1492
=7120
10.原式=405*24
=9720
以后不懂得都可以问我!!

问题补充：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

题目呢？