Quadratic Transformations urgent

(Angry)

I need a little help with this problem...

__Number of coputers produced-Profit__

50---------------------------$5100

100--------------------------$5600

150--------------------------$1100

A-Find a quadratic function that describes the profit as a function of the number of computers produced.

B-Predict the number of computers that need to be produced to maximize the profit.

C-Predict the max profit, assuming that all business conditions stay the same.

For a i have -1.2x^2+189.7+-1390.... i dont know if its right

And for b i found 79 computers....

and for c i found $6107.1

i dont think this makes since... this would mean that between 50-100 it would have hit its max and dropped