Answer:
21 feets
Step-by-step explanation:
Since the lure is 21 feets beneath the water surface,
The the elevation of the lure is - 21 feets
If the surface of water = x
Then current distance of lure equals :
x - 21
To obtain the nunber of feets to reach the water surface ;
x - 21 = 0
x = 21 feets
