X coefficient Y coefficient
Objective?
Subject to Constraints C1 and C2:
X Y
Constant
X,Y >0
Draw line 1, get endpoints
then connect points.
(X, Y)  
Line 1, vertical intercept
Line 1, horizontal intercept
Draw line 2, get endpoints
then connect points.
(X, Y)  
Line 2, vertical intercept
Line 2, horizontal intercept
Lines cross each other:
Test points (X,Y): Z
Coordinates (X,Y) Z
Maximum Z
Minimum Z