The formula for an area of a circle is A= pi(r)^2
so if you plug in 5 to r (because it’s the radius) you should get A= 78.5
The area is another way of say perimeter. it's the inside area of the rectangle
Since she has painted 60% of her bedroom so far, 40% must remain. In order to know how many square feet that is, we take the total amount of square feet she needs to paint and multiply it by 0.4
45*0.4 = 18 square feet
X stands for the score of her first test
Y stands for the score of her second test
I'm not sure how you obtained -5 as your answer but this is the mathematical explanation. hope this helps!