problem question

Question

The manager of a fish store has water that is 10% salt and water that is 25% salt. He needs to fill an aquarium with 10 gallons of water that is 20% salt.

use a linear equation to find how many gallons of each type of salt water to combine

Answer 1

Let x = gallons of 10% salt

Let 10 gallons - x = gallons of 25% salt

(x)(10%) + (10-x)(25%) = (10)(20%)

10x + 250 - 25x = 200

-15x = - 50

15x = 50 

x = 3.33 gallons of 10% salt + 6.67 gallons of 25% salt