(5/7 - 1/3) + (1/4 - 1/5) + 0.25
1. 5/7-1/3=5*3/21-7/21=(15-7)/21=8/21 2.1/4-1/5=5/20-4/20=1/20 3.8/21+1/20=(8*20+21)/420=181/420 4.181/420+0.25=181/420+25/100=181/420+1/4=181/420+105/420=286/420=143/210