A frog jumps vertically upward from a 20m tall building with an initial velocity of 10m/s.
How high above the ground will the frog reach?

How do you set up this problem

Use your motion formulae.

Here, you make use of v^2 = u^2 + 2as

v = final velocity
u = initial velocity
a = acceleration
s = displacement.

Taking the upward direction as positive;
u = +10m/s
v = 0 m/s (when it reaches the max height, it is temporarily at rest)
a = -9.81 m/s^2 (downward direction explaining the -ve sign)
s = displacement (the one you're looking for)

Solve for s, and you're done! :)

I hope it helped! :)