Final answer:
The algebraic expression to describe how much Michelle will spend before sales tax based on purchasing the phone and any number of apps is: Total cost = cost of phone + (cost of one app x number of apps). If Michelle buys the phone and 8 apps, the total cost will be $24.91.
Step-by-step explanation:
The algebraic expression to describe how much Michelle will spend before sales tax based on purchasing the phone and any number of apps can be written as:
Total cost = cost of phone + (cost of one app x number of apps)
Using this expression, if Michelle buys the phone and 8 apps, we can substitute the values:
Total cost = $8.99 + ($1.99 x 8)
Calculating this expression, we get:
Total cost = $8.99 + $15.92 = $24.91