The maximum amount you can spend before tax and tip is:
$ 12.397
x represents the cost before tax and tip.
Also, we have a total of $ 15 to spend on.
The equation which represents the total cost of our meal is given by:
c= x+0.06x+0.15x
This means that:
[tex]c\leq 15\\\\i.e.\\\\x+0.06x+0.15x\leq 15\\\\1.21x\leq 15\\\\x\leq \dfrac{15}{1.21}\\\\x\leq 12.397[/tex]
The answer is: $ 12.397