100 lbs = 1 lb of melon 99 lb water
Let "x" be weight of water:
percentage = weight of water / (1 lb melon + water)
.98 = x / (1 lb melon + x)
.98 = x / 1 +x
.98 + .98x = x
.98 = .02x
x = 49
49 lbs of water
1 lb melon + 49 lbs water = 50 lbs total
49 / 50 = 98%
Therefore, 50 POUNDS of water evaporated