$21.$ Max Z $=5$x$1+6$x$2$

Subject to:

$17$x$1+8$x$2<=136$

$3$x$1+5$x$2<=36$

x$1,$ x$2>=0$ and integer

What is the optimal solution?

A$)$x$1=5,$ x$2=4,$ Z $=49$

B$)$x$1=4,$ x$2=6,$ Z $=56$

C$)$x$1=6,$ x$2=4,$ Z $=54$

D$)$x$1=5\mathrm{.}81,$ x$2=4\mathrm{.}63,$ Z $=56\mathrm{.}91$