Bicycle Sales and Advertising Days

In a small town, the number of bicycles sold by a local store in a week can be modeled by the equation:

$$ y = 15x + 20 $$

where:

• y = number of bicycles sold
• x = the number of advertising days per week (a maximum of 7 days)

During one particular week, the store implemented a new advertising campaign and recorded sales totaling 105 bicycles. What was the number of advertising days, $x$, the store utilized during that week? Round your answer to the nearest hundredth if necessary.