You make a trip to your neighborhood’s convenience store every week to buy boxes of cookies for your Sunday afternoon tea party.

Question

This is for Alegbra 1 honors for middle school and I really need help because I am not understanding. It would not let me fit the whole problem but the rest is 

 

Taking the city bus costs you $2.50. Each box of cookies costs $1.25 per box. Write a function to represent the situation.

Answer 1

Weekly cost =   $2.50   +  $1.25x             [where x=number of boxes of cookies bought]

Answer 2

Hello Lily,

 

It looks like the problem is asking you to write a function to show how much money you spend on your weekly tea parties.

 

Traditionally, the host provides tea and cookies, so let's assume that you're having the tea party at your house. This means that we only need to think about trips that you make to your neighborhood convenience store. You could take a stroll through your neighborhood to reach the store, or you could take the bus (maybe if it's raining or snowing).

 

We need to make up a variable to represent the number of bus tickets you buy during the week. Let's call it t, for "Ticket."

 

We also need to make up a variable to represent the number of cookie boxes you buy. Let's call it y, for "Yummy Snacks."

 

Really, you could use any letter of the alphabet you like to represent these things. You could even use letters from other alphabets (scientists really like to use letters from the Greek alphabet). Some mathematicians will even use symbols (like ♠, ♣, ♥, or ♦).

 

Anyway, we can construct a function that shows how much money we're spending each week. The function uses two different variables, so we have to call it f (of t and y):

 

     f(t, y) = $2.50t + $1.25y

 

We multiplied t by $2.50 because that's how much each ticket costs, and we did the same for y and $1.25.

 

So, let's say for a sunny week, we use the bus zero times (t = 0), and we buy three boxes of cookies (y = 3). Then, if we plug in those values, we'll get the total amount we spent that week:

 

     f(0, 3) = $2.50(0) + $1.25(3)

     f(0, 3) = $3.75

 

But maybe the next week is rainy, so we use the bus. We need to buy two tickets for a round trip (t = 2), and we have extra guests coming, so we buy five boxes of cookies (y = 5). Then:

 

     f(2, 5) = $2.50(2) + $1.25(5)

     f(2, 5) = $11.25

 

Hopefully, this answer helps you understand how functions work, and how we can use them practically.

 

Call on us if you ever want more help, Lily!  :)