Question

递等式计算．
12.7+2.85+7.3+2.15
0.78×6.4-0.78×5.4
12.5×4.6×0.8
72÷（1.84+2.96）×1.8．

Answer 1

（1）12.7+2.85+7.3+2.15
=（12.7+7.3）+（2.15+2.85）
=20+5
=25；

（2）0.78×6.4-0.78×5.4
=0.78×（6.4-5.4）
=0.78×1
=0.78；

（3）12.5×4.6×0.8
=12.5×0.8×4.6
=10×4.6
=46；

（4）72÷（1.84+2.96）×1.8
=72÷4.8×1.8
=15×1.8
=27．