## gdogthegirl 3 years ago Help please!? The sales tax on a new car varies directly to(or is directly proportional) the price of the car. If \$1,800 in sales tax is paid for a \$25,000 car. what is the purchase price of a car worth \$1,600 in sales tax? Im totally lost when it comes to variations :(

1. gdogthegirl

could you show the steps too?

2. tcarroll010

It's a question in proportions. 1800 is to 25000 as 1600 is to x. Are you with me so far?

3. gdogthegirl

yes

4. gdogthegirl

but im not supposed to use proportions

5. gdogthegirl

its for variations like this is a direct variation

6. tcarroll010

"varies directly" is the same as proportions. You will use an equation like a/b = c/x.

7. tcarroll010

1800 = a. 25000 = b. 1600 = c. Just get x

8. li_za12

25000/1800 = x/1600 25000/1800 = 13.89 1800 x 13.89 = 25 1600 x 13.89 = x

9. gdogthegirl

the equation they gave to use to use was y=kx ^{n} \]

10. gdogthegirl

y=kx squared to n

11. tcarroll010

What is your value for k?

12. gdogthegirl

that what i dont know