Solve for x. x/3≤−6 a) x≤−18 b) x≤−2 c) x≥−2 d) x≥−18

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?