练习十七1.1.算一算,比一比。算一算,比一比。8+4+7=13-6+3=8+(4+7)=13-(6+3)=19191041211 7 92.2.5+(2+3)=7+(14-9)=40+20+8=90-(16+4)=10681270 560 52045-5-3=45-5-3=45-(5+3)=45-(5+3)=4037(箱)837(箱)54-5+30=76-6-8=87-9-10=65-7-40=43-(3+27)=39-(9-5)=796862184.4.13354978307058 45.5.819351628416.6.338276633364897372-40=32(人)已经检查了的人中,有多少人不是近视?40-6=34(人)8.8.36+40+2=59-9-20=63-30+5=30+(11-4)=47+(18-9)=40+(15-8)=75-(10+50)=78303837564715765033 7 9 760538267656568270