105×12-635)÷25
=(1260-635)÷25
=625÷25
=25
①(105×12-635)÷25
=(1260-635)÷25
=625÷25
=25
②[458-(85+28)]÷23
=[458-113]÷23
=345÷23
=15
③630×[840÷(240-212)]
=630×[840÷28]
=630×30
=18900
④288÷[(26-14)×8]
=288÷[12×8]
=288÷96
=3