Suppose a heated baby pool with 21 gallons of water contains a mixture of cold water at 65°F and hot water at 128°F. The desired temperature is 82°F. How many gallons of water at 65°F are needed when rounded to the tenth’s place? Please show me the steps.

Question

anonymous · Answer

it's from  8th grade math tournament

anonymous · Answer

algebra1

anonymous · Answer

Which one is that?

anonymous · Answer

x + y = 21
$$\frac{65x + 128y}{21} = 82$$

mertsj · Answer

65x +128(21-x)=82(21+x)

anonymous · Answer

x = 21 - y

65 (21 - y) + 128y = 1722

1365 - 65y + 128y = 1722

63y = 357

y = 357/63

x = 21 - 357/63 = about 15.3 gallons

mertsj · Answer

That can't be right, Moneybird, because the final volume will not be 21 gallons

anonymous · Answer

with 21 gallons of water contains a mixture of cold water at 65°F and hot water at 128°F. It didn't say "add" and it says "needed"

anonymous · Answer

thanks