SOLUTION
1)
The maximum profit the florist will earn from selling celebration bouquets can be found at the vertex point of the graph plot of P(X):

The maximum profit the florist will earn from selling celebration bouquets is $675
2)
The florist will break even when there is no profit or loss.
And looking at the plot on the x-axis, that will be at 20 one-dollar decreases.
3)The interval of the number of one-dollar decreases for which the florist makes a profit from celebration bouquets is (0,20)