Answer:
The minimum value is
or 
Step-by-step explanation:
we have

This is the equation a vertical parabola open upward
The vertex represent a minimum
The general equation in vertex form is

where
(h,k) is the vertex
Convert the given function in vertex form

Factor 2

Complete the square


Rewrite as perfect squares

The vertex is the point 
5x = 50
Where x represents the (equal) amount of money each player contributed
As you can see, you can easily solve the equation above to get:
x = 10
Each player contributed $10 toward a $50 gift.