mixed-integer linear program Max 1x1 1

Consider the following mixed-integer linear program:
Max1x1 + 1x2
s.t.
7x1 + 9x2 = 63
9x1 + 5x2 = 45
3x1 + 1x2 = 12
x1, x2 ?Y 0 and x2 integer
a. Graph the constraints for this problem. Indicate on your graph all feasible mixed-integer solutions.
b. Find the optimal solution to the LP Relaxation. Round the value of x2 down to find a feasible mixed-integer solution. Specify upper and lower bounds on the value of the optimal solution to the mixed-integer linear program.
c. Find the optimal solution to the mixed-integer linear program.