5/9乘79有6/17加50乘1/9加11/9乘5/17

问题描述:

5/9乘79有6/17加50乘1/9加11/9乘5/17

先把5/9X79又16/17等价为5/9X(80-1/17) 即5/9X80-5/9X(1/17)
原式=5/9X80-5/9X(1/17)+50X1/9+1/9X5/17
=5/9X80+50X1/9
=1/9X(400+50)
=50