▪1) 117-63×15÷21+428 = 117-945÷21+428 = 117-45+428 = 72+428 = 500
▪2) 51+195×18÷130-78 = 51+3510÷130-78 = 51+27-78 = 78-78 = 0
▪3) (2323+3760-14×304)÷203 = (2323+3760-4256)÷203 = (6083 - 4256)÷203 = 1827÷203 = 9
▪4) (49×104-2891+512)÷247 = (5096-2891+512)÷247 = (2205+512)÷247 = 2717÷247= 11