We can first find how deep the drill could dig for an hour(a day consist of 24 hours):
60÷24
=2.5feet
We can then find how deep it would be for 15 hours:
2.5×15
=37.5 feet
The answer of a is 37.5feet.
For b,we can find the time by deviding the height by it's feet per hour:
143.6÷2.5
=57.44hours
Thus the answer of b is 57.44hours.
Hope it helps!
