15分之3加11分之4减13分之3等于几
问题描述：
15分之3加11分之4减13分之3等于几
答
3/15 + 4/11 - 3/13
=1/5 + 4/11 - 3/13
=11/55 + 20/55 - 3/13
=31/55 - 3/13
=(31*13-3*55)/(55*13)
=238/715