1. (2024一下·宿城月考)  

78-6=	81+5=	65-5=	87-9=	72+5-9=
3+80=	77-70=	40+30＝	14-9=	10+7-8=
13-5=	90-80＝	98-8=	13+20=	80-20+8=
20+80=	12+26=	55+20=	21+5=	13-9+20=