Hm.. I'll try and help guide you step by step. I first recommend for you to plug in the numbers in the variables.
a=v2-v1/t2-t1 is your equation
Since we have everything but v2, we leave that variable alone and plug everything else.
9.8 = v2 - 19.6 / 5 - 2
Let's first solve 5-2 to make this equation look as simplified as possible.
9.8 = v2 - 19.7 / 3
To solve for v2, you're gonna have to isolate the variable. Let's first get rid of that 3 first.
To remove the 3, it must be canceled out by -3. Since the 3 is dividing, you would multiply both sides by -3.
9.8 * -3 = v2 - 19.6 / 3 (-3)
Now our simplified equation looks like
-29.4 = v2 - 19.6
We need to finally move -19.6 over by canceling it to isolate the v2. The opposite of subtracting is adding. So you add 19.6 to both sides.
-29.4 + 19.6 = v2 - 19.6 (+19.6)
You have the answer now
-9.8 = v2
