6 3/8 minus 2 5/6 minus 2 1/4
convert the mixed numbers to improper fractions
51/8 - 17/5 - 9/4 to subtract these we need a common denominator of 40.
(51*5)/40 - (17*8)/40 - (9*10)/40
255/40 - 136/40 - 90/40
255 - 136/40 - 90/40
119/40 - 90/40
119-90 /40
29/40