Replacing a square window with a rectangular one. the new window is 3ft wider and 2ft higher than the square one. the area is 30 ft. how long was a side of the original square window?

So your equation would be x+3 times x+2 = 30
When you factor this out, you get x^2 + 5x + 6 = 30
Then you have to move the 30 over so you can set it equal to zero, so subtract 30 from both sides of the equal sign. 
You now have X^2 + 5x -24 =0
Here you'd try to refactor, but unfortunately that doesn't work in this equation so you have to use the quadratic formula. 

Look up the formula if you don't know it, it would be more confusing if I tried to type it out. Just keep in mind that for this equation, a=1 b=5 and c= -24.