Question 983523
x, fish
y, chicken
c, cost
4x+3y=c


The restriction:  c is between 11 and 15 dollars, inclusive.

{{{11<=4x+3y<=15}}}


{{{highlight(system(11<=4x+3y,4x+3y<=15))}}}



The possible solutions are the POSITIVE x y values BETWEEN the two lines.
{{{graph(300,300,-2,6,-2,6,y=-4x/3+11/3,-4x/3+5)}}}