To Find :
How many gallons of a 80% antifreeze solution must be mixed with 100 gallons of 20% antifreeze to get a mixture that is 70% antifreeze.
Solution :
Let, x gallons of 80% antifreeze solution is required :
So,
[tex](x \times 80) + ( 100 \times 20 ) = (x + 100 )\times 70\\\\8x + 200 = 7( x + 100)\\\\x = 500[/tex]
Therefore, 500 gallons of 80% antifreeze solution is required.
