15*(-3/4)-15*(-2/3) 8*(-2/5)-(-4)*(-2/9)+(-8)*3/5

问题描述:

15*(-3/4)-15*(-2/3) 8*(-2/5)-(-4)*(-2/9)+(-8)*3/5

15*(-3/4)-15*(-2/3)
=15*(-3/4)+15*(2/3)
=15*(-3/4+2/3)
=15*(-9/12+8/12)
=15*(-1/12)
=-15/12
=-5/4
=负一又四分之一.
8*(-2/5)-(-4)*(-2/9)+(-8)*3/5
=-8*2/5-8*3/5-4*2/9
=-8(2/5+3/5)-8/9
=-8-8/9
=-8(1+1/9)
=-8*10/9
=-80/9=负八又九分之八.