Simple Harmonic Motion equation rearrangement?

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Homework Statement

Hello! I have a physics homework question I just need help at!
What I am supposed to do is calculate the value for free-fall acceleration, ag, for each of my trials that I did in my lab. I supposed to use the equation for the period of the simple pendulum, T=2π√l/g, but I have to rearrange it to solve for ag. How would I do that?

Homework Equations

Here are some sample values I used in my lab:
Length: 1 meter
Period: 20.1 seconds

The Attempt at a Solution

 

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*Update*
I figured it out!