Question

State sales tax y is directly proportional to retail price x.
An item that sells for 150 dollars has a sales tax of 12.32 dollars.

Find a mathematical model that gives the amount of sales tax y in terms of the retail price x.

Answer 1

23x24=? You gotta use a calculator if needed.

Answer 2

since y and x are directly proportional, it can be written as y= c x, c is coefficient of proportionality, so, we get c=y/x, for example  the rapport or proportionality  between y and x is given by  y/x=12.32/150 =0.08, y/x=0.08,  that means state sales tax is  8% for all  retail price.