A table of values of a linear function z=f(x,y) is given below: xly y=1 y=4 y=7 x=1.5 -0.25-1.75 -3.25 x=2 0.5 -1 -2.5 x=2.5 1.25 -0.25 -1.75 (a) Determine the linear function z=f(x,y). (b) Evaluate the function at (2,3), i.e., find f(2,3). Enter your answer in the blank below. Your