8.8-0.56*(2又5/12-1又19/60+2.275)/7分之20
原式= 8.8-0.56(2+5/12-1-9/60+2+11/40)*20/7
= 8.8-0.56(3+5/12-19/60+11/40)*20/7
= 8.8-0.56(3+5/12-19/60+11/40)*20/7
= 8.8-0.56(3+3/8)*20/7
= 8.8-2/25*7(27/8)*20/7
= 8.8-27/5
=44/5-27/5
=17/5
=3.4