Question 161668
Let x=x1 and y=x2



So the equations are 


z = 10x + 9y,

x+y= 30,
x+y>= 25,
2x+y<= 40




1) First plot the last three equations (you need to solve for y)


2) Find the intersections of the three equations. 


3) Plug in the coordinates of the intersection into z = 10x + 9y


For example one intersection is (10,15) which means that x=10 and y=15.


The largest value of z will maximize z = 10x + 9y