Answer:
or 12.5
Step-by-step explanation:
So if 25 - x items are sold, and they each cost x, we can write an equation for the revenue to be
y = (25 - x)x
The vertex of this equation will represent the maximum revenue. So we need to write this equation in vertex form so we can find the vertex.
Vertex from is
y = a(x - h)^2+ k,
where (h,k) represent the vertex.
the vertex form of this equation would be

And the vertex would be

This means the maximum revenue will occur when x = 25/2