Let's denote X as the number of pairs of footwear sold last year.
Boots sold: 118214 (pair)
Sandals sold= 37092 + boots sold= 37092+ 118214= 155306
Sneakers sold= 124417+ boots sold= 124417+ 118214= 242631
footwear sold= boots sold+ sandals sold+ sneakers sold
= 118214 + 155306 + 242631 = 516151