Please use the
code tag
Also, cleaning up your code might help (or make it more easy to find the error)
public boolean isPoor(double housingCost, double foodCost){ return ((housingCost + (foodCost * size)) > (income / 2));}
Also to find the error, using:
System.out.println(someValue);
helps alot. The problem with your define boolean isPoor; but also it in a method (public boolean isPoor()), simply call isPoor(par1, par2) when you want the result.