Let
be the most the manager can pay the suppliers.
Then, we know from the information given in the question that the manager needs a 30% markup based on cost.
Therefore, the guiding equation will be:
![x+\frac{30}{100}x\leq 10](https://tex.z-dn.net/?f=%20x%2B%5Cfrac%7B30%7D%7B100%7Dx%5Cleq%2010%20%20)
because $10 is the most people will pay for a neck warmer.
Thus, the above equation will become:
![x+0.3x\leq 10](https://tex.z-dn.net/?f=%20x%2B0.3x%5Cleq%2010%20)
![1.3x\leq 10](https://tex.z-dn.net/?f=%201.3x%5Cleq%2010%20)
![x\leq \frac{10}{1.3}=7.69](https://tex.z-dn.net/?f=%20x%5Cleq%20%5Cfrac%7B10%7D%7B1.3%7D%3D7.69%20%20)
![\therefore x\leq 7.69](https://tex.z-dn.net/?f=%20%5Ctherefore%20x%5Cleq%207.69%20)
Thus, the most a manager can pay the suppliers for neck warmers and still keep the selling price at $10 is $7.69