In a store window, there was a box of berries having a total weight of $200$ kg. The berries were $95\%$ water, by weight. After two days in the sun, the water content of the berries was only $90\%$, by weight. What was the total weight of the berries after two days, in kg?
The berries are 5% non-water by dry weight, since $100\% - 95\% = 5\%$. Call the weight of the non-water $x$ kg. Then $x/0.05 = 200$ kg, so $x = 10$ kg, and the weight of the berries after two days is $10 + 190 = \boxed{200}$ kg.
