数学题：7/10除以13+12/13x7/10简便算法还有要简便算法的：(3/4+1/4除以3/10)x12(5/8+37.5%)除以(21/10-209%)十分钟内解答,急啊

Question

数学题：7/10除以13+12/13x7/10简便算法
还有要简便算法的：(3/4+1/4除以3/10)x12
(5/8+37.5%)除以(21/10-209%)
十分钟内解答,急啊

Answer 1

7/10÷13+12/13x7/10
=7/10x1/13+7/10x12/13
=7/10x(1/13+12/13)
=7/10x1
=7/10

(3/4+1/4÷3/10)x12
=3/4x12+1/4x12÷3/10
=9+3x10/3
=9+10
=19

(5/8+37.5%)÷(21/10-209%)
=(5/8+3/8)÷(2.1-2.09)
=1÷0.01
=100