1-5/12+4/15+1/12-14/15-39/20
问题描述:
1-5/12+4/15+1/12-14/15-39/20
答
1-5/12+4/15+1/12-14/15-39/20
=1-(5/12-1/12)-(14/15-4/15)-39/20
=1-1/3-2/3-39/20
=1-(1/3+2/3)-39/20
=1-1-39/20
=-39/20