怎样简便就怎样算:(250+25)×4;42×42+42×58;99×57;125×32
6-3= 3+3= 7-5= 5+2=
9-4= 9-5= 4+5=
10-4= 10-6= 4+6=
5+2= 7-5= 7-2=
4+1= 5-1= 5-4=