System of equations when 45 animals with 7more cats than dogs

What number should be added to both sides of the equation to complete this square? x^2-10x=7

True or false? a circle could be circumscribed about the quadrilateral below.

Which values of p and q result in an equation with exactly one solution? px-43=-42x+q choose all answers that apply: a) p=-43 and q=-43 b) p=42 and q=43 c) p=43 and q=−42 d) p=42 and q=42