Mikes fishing lure Is 21 feet below the surface of the water how many feet does he need to reel in his lyre to reach the surface of the water?

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