Algebra 1 writing a function rule

Question

Write a function rule to describe each statement:

-the distance you walk at 250 ft/min

-change from a $20 bill when buying gas at $1.15 per gallon

-the amount of money in a savings account into which you deposit $5 each week

Answer 1

d(t)= 250t d=feet, t=minutes

c(g)= 20-1.15g c=change in dollars, g=gallons purchased

m(w) = 5w m=dollars after w weeks

or use f(x)

each time

f(x)= 250x

f(x) =20-1.15x

f(x) =5x

choice of letters is arbitrary

but using letters related to the problem makes it easier to know what the letters stand for