The equation needed to save this amount is A = 25x + 130, where A is the total amount had and x is the amount of weeks from the start.
You can find this equation by noting that even at 0 weeks, she has 130. Then the rate of growth (which needs to be multiplied by weeks) is 25.
To solve this for $600, we simply put in 600 for A and solve for x.
A = 25x + 130
600 = 25x + 130
470 = 25x
18.8 = x
So if we are rounding up to whole weeks, it would take 19.