42+8= 52-6= 37+6= 26+7=
18-8= 19-5= 4+14= 15-6=
20-5= 2+16= 60+( )=75 ( )=19+20
( ) ( ) ( ) ( )
47->39 +78<80 89->88-9 50+<48+9
计算:54-8=?
想:先算
再算