Question

If you wanted to mix pure methane with water and end up with 100 gallons of 90% methane, how many gallons of each should you use?

Answer 1

`90` gallon of pure methane and `10` gallon of water.

Explanation:

`100` gallons of `90%` methane contains

`100xx90/100=90` gallon of pure methane

and hence water is `100-90=10` gallon of water.