?% of 280 + 18% of 550 = 143.8 (a) 11 (b) 18 (c) 21 (d) 16 (e) None of these
(×/100)*280+(18/100)*550=143.8 (×*280)+(18*550)=143.8*100 (×*280)+9900=14380 (×*280)=14380-9900 (×*280)=4480 x=4480/280 x=16