?% of 280 + 18% of 550 = 143.8 (a) 11 (b) 18 (c) 21 (d) 16 (e) None of these
280*(?) +550*18/100=143.8
=280*(?) /100+550*18/100=143.8
=280(14)*(?) /100(5) + 550*18/100=143.8
=14*(?)/5+99=143.8
=14*(?)/5=143.8-99
=14*(?)/5=44.8
=14*(?) = 44.8*5
=14*(?) =224
(?)=224/14
(?)=16