Find the absolute maximum and minimum values of the function, subject to the given constraints.
k(x,y) = − x^2 – y^2 + 10x+10y; 0≤x≤6, y≥0, and x + y ≤ 12
The minimum value of k is _____________ (Simplify your answer.)
The maximum value of k is __________ (Simplify your answer.)