540﹣70=                  3×3×3=               5×4+4=
63÷（3×3 ）=            72﹣2﹣30=             1800+900=
55÷5=                    68﹣27﹣13=            86﹣（35﹣14）=
110+120+130+140+150+160+170+180+190=