David and josh are both practicing for an upcoming swim tournament. every week, david swims for 3x hours at an average speed of x laps per hour. josh swims 5 more hours per week than david, but at an average speed that is 4 laps per hour less than david's average speed. which of the following functions will give the total distance, in laps, that josh swims each week? a) f(x)=3x^2-17x+20 b) f(x)=3x^2+7x-20 c) f(x)=3x^2-7x-20 d) f(x)=3x^2+17x+20