Find the Average Rate of Change Illustrated in the Graph $\$ 1.90$

Multiple Choice

Find the average rate of change illustrated in the graph.
-Regrind, Inc. regrinds used typewriter platens. The variable cost to regrind each platen is $\$ 1.90$ . The total cost to regrind 100 platens is $\$ 300$ . Find the linear cost function to regrind platens. If reground platens sell for $\$ 8.70$ each, how many must be reground and sold to break even?

A) $C ( x ) = 1.90 x + 110 ; 11$ platens
B) $C ( x ) = 1.90 x + 110 ; 17$ platens
C) $C ( x ) = 1.90 x + 300 ; 29$ platens
D) $C ( x ) = 1.90 x + 300 ; 45$ platens