2y - x = 5
x^2 + y^2 - 25 = 0
x = 2y - 5
(2y-5)^2 + y^2 - 25 = 0
(2y-5)(2y-5) + y^2 - 25 = 0
4y^2 - 20y + 25 + y^2 - 25 = 0
5y^2 - 20y = 0
y = 0 , y = 4
x = 2y - 5 , when y = 0
x = - 5
x = 2y - 5 , when y = 4
x = 8 - 5
x = 3
It's more efficient to hold a random drawing because the probability is higher.

For every 2 person, 1 person gets to go to the concert.
Answer is 1/2 aka 0.5 aka 50%
Hope this helps. - M
I can't answer your question without a picture... Sorry.
Answer:
A prime number is a number that can only be divided by 1 and itself.