Calculations for 1,2,3,and 5 look spot on. Nice!
I see that instructions ask for sketches which you didn't provide. If you have sketches, and you compare #1 and #4 you will see that the magnitudes of the areas are equal. To simplify #4 you could shift the curve up 4. That integral you've already done in #1. Then at the end recognize that the area is under the x axis so that makes it negative.
Or even easier