3/4 * 5/6 - 3/10 ÷ 24
=5/8 - 1/80
=49/80
（8.75-3.25）÷ 2.5 + 1.05
=5.5÷2.5 +1.05
= 2.2+1.05
=3.25
1/5 * 47/10 + 53/10 *20%
=47/50 + 53/50
=2能简便的要简便已经简便了。