Store buys phones for $12 sells them at a markup of 250%. If the markup rate is the constant of proportionality in the equation y = kx write an equation that can be used to find the markup on the cost x of a phone.

The equation represents the function f, and the graph represents the function g. f(x)=3(5/2)^x determine the relationship between the growth factors of f and g. a. the growth factor of g is twice the growth factor of f. b. the growth factor of f is twice the growth factor of g. c. the growth factor of f is 2.5 times the growth factor of g. d. the growth factor of f is the same as the growth factor of g.