The task text does not mention it, but it can be assumed that it is about a bottle of the same volume. Thus, the price of the fabric softener has increased by a factor of $\frac{49}{13.7} \approx 3.576$.

However, the quality has also changed, as previously 15 liters required $\frac{1}{2}$ cup, now 8 liters require 1 cup of fabric softener.

So, in the first case, 1201 liters required 4 cups, while in the second case, 1201 liters require 15 cups of fabric softener, which represents a $\frac{15}{4}=3.75$-fold deterioration.

Thus, the total increase is approximately $3.576 \cdot 3.75=13.41$ times, which corresponds to a price increase of about $1200\%$.
A bottle of "Comfort" fabric softener used to cost $13.70 \mathrm{Ft}$, from which $1 / 2$ a cup was needed for 15 liters of water. The new formula "Comfort" now costs 49 forints. From this, 1 cup is needed for 8 liters of water. By what percentage did the fabric softener become more expensive?