posted by bob .
if 25 ml of sugar is mixed with 299 ml of water and then 50 ml of water is poured out, how much sugar remains in the 150 ml of wtare?
assuming that adding the sugar does not change the volume of the fluid, and assuming that you meant 200ml, since 50+150=200,
50ml is 1/4 of the fluid.
So, 1/4 of the sugar is poured out, leaving 3/4*25 = 18.75 ml.