Applications (Mixtures, Distance, etc.)

Question

If you wanted to mix pure methane with water and end up with 130 gallons of 75% methane, how many gallons of each should you use?

Answer 1

0.75 of 130 gallons is methane

Answer 2

Here x gallons of water plus y gallons of methane equals 130 gallons of 

water-methane mixture.

Also reason that y = 3x for a 25% water/75% methane mixture.

Then construct:

x/130 + 3x/130 = 130/130 for 1 entire 130-gallon water/methane solution.

Extract from this last that x + 3x or 4x = 130 or x = 32.5.

The quantities sought would then be 

[32.5 gallons of water, 97.5 gallons of methane].