That means if 2 frogs (middle and one outer) jumped, then the weight distribution of the last remaining outer frog would have been too much, therefore tipping the lily pad off balance and throwing the remaining frog into the water. That was the easy explanation.
Medusa first appeared in Fantastic Four #36 (1965), and was created by Stan Lee and Jack Kirby. She appears first in flashback, then in costume as part of the fledgling Frightful Four. She appears in #38, 41, 42, 43, 44-48 and in various subplot glimpses from #49-62. The Inhumans also appear in Fantastic Four # 82-83, with Medusa.
She is the only one of the three sisters known as Gorgons that was born a mortal. Medusa was once very beautiful but she was cursed by Athena. The godess Athena gave her snakes for hair ,and made her so ugly that anyone that stared at her turned to stone.