First you need to change 45 feet to 540 inches.
Now you can compare the two ratios:
1 : 25 and 25 : 540
We now need to change the second ratio to a unit rate:
25:540 as a unit rate would be 1 : 21.6 and this is steeper than the a 1 : 25 drop
So, your answer would be: pipe drops to much vertically to function properly
