Answer:
The value belonging to the green box is b
Explanation:
QP uses the points Q and P
Q is (0,-a)
P is (b,-c)
The distance between the two points can be calculated using the distance formula;
D = √(x2-x1)^2 + (y2-y1)^2
(x1,y1) = (0,-a)
(x2,y2) = (b,-c)
D = √(b-0)^2 + (-c + a)^2
D = √(b)^2 + (-c + a)^2