she has 180 dollars to start off with so you want to add that to the total cost. Then she makes 60 a day sbyt only actually saves 50 of it so +50x (thats the way i see it. The way they put it in the question is questionable. Dont know if she puts off the 50 or the 10)
The amount she started off with + how much she saves from working per day = total amount she needs