You can inscribe a quadrilateral inside a circle if and only if its opposite angles are supplementar. In your case, this means that
Since we're interested in the angle R, let's use the second part of the equalities above to substitute the given values for R and P:
The left hand side can be simplified to 
, so if we subtract 8 from both sides the equation becomes
Since 
, we can compute the angle R by plugging this value into its formula:
Here's what I got for the first question.
Did you want answers for the second one? I couldn't read that part of the image very well, if you did.
Answer:
12 servings!
Step-by-step explanation:
1/4 equals 0.25 gallons, 1/2 gallons is 0.5, so Will will have a mix of 0.75 gallons. If each serving is 1/16 and 1/16 equals 0.0625, divide 0.75 by 0.0625 = 12 servings.
The probability is 9/16.
This is because in the simulation, 9 of the results had 2 or 3 girls, and there was a total of 16 choices.
