Video solution:

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Written solution:

We can let $g$ be the number of green frogs and $y$ be the number of yellow frogs. Initially, we have $g=3y$. Then, after some frogs moved, we have the following proportion: $$\dfrac{g+5-3}{y+3-5} = \dfrac{4}{1}.$$

Substituting $3y$ for $g$ will allow us to determine the number of yellow frogs originally ($y$): $$\dfrac{3y+2}{y-2} = 4$$ $$3y+2 = 4(y-2) = 4y-8$$ $$y = 10$$

Hence, there were $10$ yellow frogs and $3 \times 10 = 30$ green frogs initially. After some frogs moved, we now have $10+3-5 = 8$ yellow frogs and $30+5-3=32$ green frogs, giving us a difference of $32-8=24$ between the number of green and yellow frogs.

Thus, E is the correct answer.