Answer:
Givens
- Layla charges $2 per day, plus a sign-up fee of $3. Notice the sign-up fee represents a fixed value, that's gonna be the constant form of the function. And $2 is the ratio of change of the function, because it a cost per day.
- Sam charges $3 per day, without extra fee. So, the ratio of change of this function is $3, and it doesn't have a constant term.
According to the given information, the linear function for Layla is:
Notice that the constant ratio of change is coefficient of the independent variable, that is, because that variable represents days, and each charges $2.
On the other hand, the linear function for Sam is:
As we said before, this expression doesn't have any constant term, because the charges are flate $3 per day, it's just that rate.
Now, to find the number of days needed to both Layla and Sam earn the same money, we just have to solve the equation
Therefore, on day three they are gonna earn the same amount of money.