I agree with viveksah and I might have done the same thing. But in general with mixture problems, I always make a quick chart that's designed to line everything up properly. In this case, the chart looked like this:
Note: The zero in the percent of water after the water evaporated is just a place holder, not a zero. I just didn't bother calculating it since it's not important.
From here, I can see that 5/8 of the new mixture are water, so 3/8 are liquid x. I chose to do the whole chart in water because water is what evaporated from the original.
whenever there's a mixture problem, there's always the whole, the percentage, and then the part. If you line it all up properly, and add down, the chart takes care of the rest.