Hey!
To find out how long it would take for both functions to equal the same thing, you would set them equal to each other, like this:
Then you would combine like terms. Keep in mind that when doing operations over the equal sign, you have to do the opposite operation. After combining like terms, you would have
So at this point, you just simplify.
It would take 5 months for the amount of money to be equal. She would save $250 with either option.
Hope this helped :)