Answer:
A. at (8,7) the maximum value is 98
Step-by-step explanation:
First draw the region, that is bounded by all inequalities. This is the triangle with vertices (6,1), (2,5) and (8,7).
Now you can see where the line f(x,y)=7x+6y intersect this region. The maximum value will be at endpoints of this region:
Thus, the maximum value of the function is 98 at the point (8,7).