54218 - 2015 : 403
= 54218 - 5
=54213

4237 × 18 - 34578
=76266-34578
=41688
2/7 + 3/7 - 1/2
= 5/7 - 1/2
= 10/14 - 7/14
= 3/14
( 5/3 + 1/3 ) × 3
= 6/3 x 3
= 2x3=6
126 × 24 - 1378
=3024-1378
=1646
2485 : 71 × 25
=35x25
=875
807642 - 2030 : 14