If you could explain how I would get this answer also that'd be great

Jocelyn makes x dollars per hour working at the grocery store and n dollars per hour babysitting. Write an expression that describes her earnings if she babysat for 25 hrs and worked at the grocery store for 15 hrs

For now, we can't get a definite answer. We can model with an equation, but we cannot find the absolute amount Jocelyn will earn, as her hourly rates are both variables. All we must do to create an equation for this is multiply the amount of hours by the rate and add. You could model like this:

25n + 15x = total amount earned