5/8-1/8+1/4=5/8-1/8+2/8=6/8=3/4
1/4等于2/8 5/8-1/8+2/8=6/8=3/4
5/8-1/8=0.5,
=5/8-1/8+2/8=4/8+2/8=6/8=3/4