Question

It cost marci 33 cents to mail a postcard and 49 cents to mail a letter. she sent either a postcard or a letter to each of 28 people and spent $13.08. let x represent the number of postcards she wrote and write an algebraic expression for each item in parts a through c.

Answer 1

24 Letters and 4 Postcards

Explanation:

We have to set up a system of equations, since we have two unknown variables. Lets say postcards is the variable "x" and letters is the variable "y".

Our first equation will be the money spent: 0.33x + 0.49y = 13.08, this comes from knowing that it costs 0.33 dollars to mail a postcard and 0.49 dollars to send a letter.

The second equation is the total sent: x + y =28.

Now we need to solve for a single variable, let's do y (or letters). If we subtract y from both sides we get: x = 28 - y.

We can plug that into our first equatino to get: 0.33(28 - y) + 0.49y = 13.08.

If we multiply things out we get: 9.24 - 0.33y + 0.49y = 13.08, and now we have like terms. 9.24 + 0.16y = 13.08.

Subtract 9.24 from both sides to get: 0.16y = 3.84

Divide both sides by 0.16 to get: y = 24.

Now we can plug this into x + y = 28 to see that x= 4.

You could make sure this is correct by solving for x instead of y and do the same process.

Hope this helps.