Question 820937
(a) & (i)
{{{y<=x}}}, directly translated from that condition described.


(ii)
Attempting cost relationship
Highest cost allowed is 4500 dollars.
{{{150x+300y<=4500}}}
Reducible to
{{{x+2y<=30}}}
Again, reworded, the cost of the guitars and violins must be less than or equal to 4500 dollars.


You did not say if you want to combine these inequalities for a solution.  This can be done easily enough checking on a graph.  Plot both equations (the two unique ones; not the unreduced cost one) as their lines, and then test any point in each of the four regions; 
What I mean to say is, graph the system:
{{{highlight(x<=y)}}} and {{{highlight(x+2y<=30)}}} onto the same coordinate system.  The reason that you want to use the REDUCED cost inequality is because it is easier to use.