Hello, struck!
We assume: .$\displaystyle \begin{array}{cccc}x & \geq & 0 & {\color{blue}[1]} \\ y & \geq & 0 & {\color{blue}[2]} \end{array}$
We have: .$\displaystyle \begin{array}{cccccccc}25x + 15y & \leq & 1800 & \;\Rightarrow\; & 5x + 3y & \leq & 360 & {\color{blue}[3]}\\
x  3y & \geq & 0 & \Rightarrow & y & \leq & \frac{1}{3}x & {\color{blue}[4]}\end{array}$
[1] and [2] places us in Quadrant 1.
Graph the line of [3]: .$\displaystyle 5x + 3y \:=\:360$
It has intercepts (72,0) and (0,120).
Graph the line and shade the region below it.
Graph the line of [4]: .$\displaystyle y \:=\:\frac{1}{3}x$
It contains the origin and has slope 1/3.
Graph the line and shade the region below it.
Your graph should look like this: Code:

(0,120)*
 *
 *
 *
 * *
 * *
 o
 *:::::*
 *:::::::::::*
 o         o  
 (72,0)
Can you finish it now?