78×21﹣531
672÷(2×3)
364+259÷7
810÷(3×3) 497÷7+266 631-31×18
①6.4×2.5×1.25
②8.5×98%
③÷4+×
④×
①12.5×(8+0.8)
②+×
③+÷
④26﹣7.28﹣12.72
⑤5.8×4.1+5.9×5.8
⑥÷(+1.4×)