3/4+5/6-7/8=9/12+10/12-7/8=19/12-7/8=38/24-21/24=17/24,24.3×2.3-5.6÷2.8=55.89-2=53.89,65.2-(5.2-10)=65.2-5.2+10=60+10=70.
