Question

If a train travels m miles in h hours and 45 minutes, what is the average speed in miles per hour ?

Answer 1

Speed = (distance covered) / (time to cover the distance).

Time = 'h' hours and 45 minutes.
45 minutes is 3/4 of an hour. (or 0.75 hour)
Total time is (h + 0.75) hours.

Speed = 'm' / (h + 0.75)

That's choice-'a'.

Answer 2

$s=m \ miles\\ t=h \ hours \ 45 \ min=h+0.75 \ hours\\ v=\frac{s}{t}\\ v=\frac{m}{h+0.75} =\frac{m}{h+\frac{3}{4}} \Rightarrow A$