Find the missing length indicated

The anwser cause i do not understand just plez

Klmn and pqrs are similar trapezoids. which side of pqrs corresponds to lm

Charlie is at an amusement park that has 18 different rides. each ride costs $1.75. the function c(r) = 1.75r represents the total amount of money that charlie will spend if he goes on r rides, but he never goes on the same one more than once. what domain and range are reasonable for the function?