I hope the given equation is :

First step to solve the above equation is to add 15 to each sides of the equation. Therefore,


Next step is to remove square root from the left side, so let's square on each sides of the equation. So,
x + 2= 12²
x + 2 = 144
x = 144 - 2
So, x = 142
So, a is the correct choice.
Hope this helps you!