SOLUTION: Right to it. I'm confused. I figured out oneproblem like this, this one I do not get. According to the AVMA, in 1987, 34.7 million households owned a dog, and 27.7 million hous

Algebra ->  Expressions-with-variables -> SOLUTION: Right to it. I'm confused. I figured out oneproblem like this, this one I do not get. According to the AVMA, in 1987, 34.7 million households owned a dog, and 27.7 million hous      Log On


   

Question 29767: Right to it. I'm confused. I figured out oneproblem like this, this one I do not get.
According to the AVMA, in 1987, 34.7 million households owned a dog, and 27.7 million households owned a cat. Since 1987, dog ownership has decreased by 0.025 million households per year, and cat ownership has increased by about 0.375 million households per year. If the trend continues, after how many years will the number of households that own dogs and cats be equal?
34.7 - 0.025 and 27.7 + 0.375 how do I calculate this?
thank you
Answer by kev82(151) About Me  (Show Source):
You can put this solution on YOUR website!
Hi,
Lets call y the number of years past 1987, so if y=3 we would be talking about 1990.
The number of millions of dogs in any given year is 34.7-0.025y because in 1987 there were 34.7 million dogs, and for every year after that, the number of dogs decreases by 0.025 million.
We can form a similar expression for the cats. Number of million cats is 27.7%2B0.375y That's because in 1987 we start with 27.7 and for every year after that ownership increases by 0.375.
So what we need to know is when the number of cats equals the number of dogs. This happens when 34.7-0.025y=27.7%2B0.375y. Hopegully you can solve this to get the answer of 17.5 years. If not write back and we can go through solving the equation.
Hope that helps,
Kev