How much water must be added to 10 gallons of 10% brine solution to decrease the concentration to 7%?
Select.
A) 0—1.5 gal  B) 1.5—3 gal  C) 3—4.5 gal  D) 4.5—6 gal  E) 6+ gal
Let amount of water that must be added in gallons to dilute concentration of brine solution = x   Amount of brine already present = 10/100 * 10= 
<gadget id="calculator">10/100 * 10</gadget>
<output>1</output>
1 gallon   1/(10+x) *100= 7   =&gt;100 = 70 + 7x   =&gt; x= 30/7 = 4.2   Answer 3—4.5 gal
<result>C</result>
How much water must be added to 10 gallons of 10% brine solution to decrease the concentration to 7%?