30% because 50-35=15 and 15 is 30% of 50 so you are losing 30%
The radius of a circle is always the square root of the number on the right. The other two numbers describe the center.
Center: (11,-15) Opposite of what's in the brackets.
Radius: sqrt(144) = 12
You simply put 40 over a hundred and 55 over n (which is the number were trying to find) so you do cross multiplication. 55 times a hundred and after you get the answer. You divide it by 40 and should get 137.5.