A company manufactures x three-speed bicycles which sell for $r and y ten-speed bicycles which sell for $s. The weekly demand and cost equations are as follows: r=-6x+3y+337 s =2x-2y + 360 C(x, y) = 110 x + 130 y + 270 At a production level of 46 three-speed bicycles and 98 ten-speed bicycles, what is the marginal profit associated with selling three-speed bicycles? O a) -$719 per three-speed bicycle O b) $536 per three-speed bicycle O c) $68 per three-speed bicycle O d) $165 per three-speed bicycle