x^2 = 7x - 10
x^2 - 7x + 10 = 0
(x - 5)(x - 2) = 0
x = 5 or x = 2
The answer is B.
50 pieces because when you do 25 times two fits you 50 fits witch can be reduced to 10
The polygon is concave because if you placed lines directly on top of every side of the polygon, one or more of the lines would intersect an existing side. In a convex polygon, if you placed lines on top of the sides they wouldn't intersect another side.
So your answer is B) Concave.