Read the example problem: Judy calls a special hotline, which costs $2 for the first minute. Each additional minute costs $1.50. Write the function of this equation. How much will a 10 minute phone call cost her?
Check to see if the two variables have a dependent relationship. In this case, the cost is contingent on time.
Write the relationship of the function: The total cost is equal to the initial cost ($2) and $1.50 times each additional minute: f(x)= $2 + $1.50(x-1).
Calculate how much 10 minutes will cost by substituting 10 for x. f(10)= $2 + $1.50(9). f(10)= $15.50. The total cost of a 10 minute phone call is $15.50.
Read the following problem: Jane is making a base of $12.50/hr and 10 percent commission on her sales. If her goal is to make $3,500 a month, what is the total amount of sales she will need to make? Assume, she works 40 hours a week for four weeks.
Check to see if the two variables have a dependent relationship. In this case, the amount of her total income is contingent on her sales.
Write the relationship of the function. The total salary= $12.50 (160 or total number of hours for the month) + 10 percent (x), where x represents the total amount of sales; f(x)=$12.50(160)+.10x
Solve the equation by substituting $3,500 for the total salary or f(x): $3500=$12.50(160)+.10x
$3500= $2000 +.10x
$1500=.10x
x=$15,000
Jane will have to make $15,000 to make her monthly goal of $3,500.