Question 10How many hours does it take a train traveling at an average rate of $40$ mph between stops to travel $a$ miles if it makes $n$ stops of $m$ minutes each?$\dfrac{3a+2mn}{120}$$3a+2mn$$\dfrac{3a+2mn}{12}$$\dfrac{a+mn}{40}$$\dfrac{a+40mn}{40}$