(8/15+5/21)*5/16*21简算答案是81/16

问题描述:

(8/15+5/21)*5/16*21简算答案是81/16

(8/15+5/21)*5/16*21
=8/15x5/16x21+5/21x21x5/16
=1/6x21+5x5/16
=7/2+25/16
=56/16+25/16
=81/16