Answer:
![x+y = 80\\325x+50y = 6, 750](https://img.qammunity.org/2021/formulas/mathematics/college/om6fobi0wc93xcyqrb4kpug5zwqr30zpe1.png)
Explanation:
Le x represents the set of new tires
Let y be the set of used tires
If a tire shop counted 80 invoices at the end of the month, then the equal that represents the total amount of invoices counted at the end of the month is:
![x+y = 80 ............ 1](https://img.qammunity.org/2021/formulas/mathematics/college/7st1d3zl4nz8fn4dbj3v1am1hwqjbecfxa.png)
If they charge $325 for a set of new tires, the total amount charged for new tires will be:
![325 * x \\325x](https://img.qammunity.org/2021/formulas/mathematics/college/7uz36ia9ztozm7ilja51bpo4zjzuec2byf.png)
If they charge $50 for a set of used tires, the total amount charged for used tires will be:
![50 * y\\50y](https://img.qammunity.org/2021/formulas/mathematics/college/y79a1thrqy11dtuv8afo0vprn6jan71a3z.png)
If the total dollar amount of the invoices was $6,750, then the expression that models the amount generated on tickets will be:
![325x+50y = 6,750 .............. 2](https://img.qammunity.org/2021/formulas/mathematics/college/mpfx0ub4x6val9tuu9184ykmqx852p6r82.png)
Hence the system of equations represents the situation is:
![x+y = 80\\325x+50y = 6, 750](https://img.qammunity.org/2021/formulas/mathematics/college/om6fobi0wc93xcyqrb4kpug5zwqr30zpe1.png)