The best way to answer this is to find counterarguments for each answer to eliminate them as a possibility. ab doesn't have to be an integer, 2.5*3=7.5 . That's also not an imaginary number so that's out. And that's also not an irrational number so that's out too. Only choice left is rational number.
Answer:
30 square feet
Step-by-step explanation:
area= length times width
1st drop- 10ft comes back up 5ft
2nd drop-5ft comes back up 2.5ft
3rd drop-2.5ft comes back up 1.25 ft
4th drop-1.25ft comes back up .625ft
(10+5) + (5+2.5) + (2.5+1.25) + (1.25) = 27.5ft