**How many gallons of a 70% antifreeze solution must be mixed with 60 gallons of 25% antifreeze to get a mixture that is 60% antifreeze?**

**You need to add ___ gallons of 70% antifreeze solution**

**Answer:**

let x be the number of gallons of 70% antifreeze that needs to be added

given that x gallons of 70% anti freeze is added to 60 gallons of 25% anti freeze to get a mixture of 60% anti freeze.

x*.7+60*.25=(x+60)*.6

.7x+15=.6x+36

(.7-.6)x=36-15

.1x=21

x=21/.1=210

210 gallons of 70% anti freeze must be mixed.