P-5=3s-15 because Pete is 20 and Sam is 10. 20-5= 15 and 3(10)-15 also equals 15. The answer is C.
Look at 36/3 = 12.
So let's try 12 along with the one before it and the one after it.
10 + 12 + 14 = 36
yay !
The third angle would be 100 degrees
Explanation: 360-85-115-60= 100