Question

Rosamaria is setting up a 20 gallon saltwater fish tank that needs to have a salt content of 3.5%. If rosamaria has water that has 2.5% salt and water that has 3.7% salt, how many gallons of the water with 3.7% salt content should rosamaria use?

Answer 1

Well, in order to find how many gallons rosamaria use, you need to use this formula :

0.037 x + 0.025 (0.20 - x) = 0.7 >>>. Multiply both side by 1000

37x + 25(20 - x) = 700

37x +500 - 25x = 700

12x = 200

x = 16.6