递等式计算.(能简算的要简算)以下三题,

问题描述:

递等式计算.(能简算的要简算)以下三题,
4/9÷10/7+5/9×7/10 1/12+3/4×2/3÷2 (1/2-5/11)×(5/9+2/13)

4/9÷10/7+5/9×7/10
=(4/9+5/9)×7/10
=1×7/10
=7/10
1/12+3/4×2/3÷2
= 1/12+3/12
=4/12
=1/3
(1/2-5/11)×(5/9+2/13)
=1/22*83/117
=83/2574