买4支铅笔需要多少钱?
7×4=
6×6-6=
8×5=
6×5+16=
6×5+41=
7×8-47=
6×7+7=
9×6-29=
53+27=
63-23=
3×(15-7)=
( )×( )=( )( )×( )=( )