①400-100÷4
②852-143+257
③(65+25)×25
④79+14×22
⑤113×(305-296)
⑥(478+285)÷7
800-11×14 (16+19)×42 56×3×2
920-706÷2
(5.2+2.8)×52
33×28-25
180÷3×6