Alexa's gross monthly pay is $3810.
to maintain her current way of life, how much should she have saved by the time she retires?

I think there are a lot of things that you need to consider with this problem. First, before you can get the amount of money that Alexa saved by her retirement, you need to consider how long is she going to live and how her money is invested. And the most important is, how much income will she need in order to provide or maintain her current lifestyle. 

Really long apparently