If there are 3 liters of 50% acid solution, there must be 1.5 liters of pure acid and 1.5 liters of another liquid.
As it is, 1.5/x = 1/2, where x = total liters of both liquids (here, 3). We use 1.5 because that's how much we have of the other liquid.
If we set 1.5/x = 1/4, x = 6. This is 3 liters more than our original solution, and we only added pure acid.
Our answer is 3 liters of pure acid.
The answer is 100 m below sea level
62 divided by 0.25 is 248
You'll need to convert both speeds into yards per minute.
12 mph = 12 mph 1760 yd 60 min
---------- * ------------ * ----------
1 mile 1 hr
Note that "miles" cancels. So does "hours." Finish this work.
Then convert 4.4 ft/sec into yards per minute.
Then, finally, compare your two rates via subtraction of the smaller from the larger.