Let's call the original side "x". so x² (area of a square) is = x² (as we can't simplify it). Then we got a 4 added to each side. So now we redefine each side as "x+4". So now we can make an equation of the area of the square. x² + 4² = 36. Now you realize that 36 is 6² so you write it. x² + 4² = 6² . Since everything is now a square just square root everything (√) So Now x + 4 = 6. Now you have a 1st degree equation now solve simple math. x = 6 - 4 = 2. The side of original square is 2in