mrs. bought 18 pens for her class. pen 1 cost $3 each, and pen 2 cost $2.50 each. She spent a total of $50. how nmany of each

Question

I am too dumb to figure out my math homework and desperately need a good grade because m already failing. Someone help me.

Answer 1

So you have two unknowns, pen 1 and pen 2.

 

Let's denote

x = number of pen1

y = number of pen2

 

In order to find x and y, you need two separate equations.

 

So what do you know? You know that she bought a mixed number of pen1 and pen2, totaling 18 pens.

 

Step 1: Write an equation that represents the total number of pens bought, using x and y.

Try to figure this out.

 

What else do you know? Pen 1 cost $3 each, Pen 2 cost $2.50 each.

 

So you know that $3 per pen1 times the number of pen1 is the amount spent on Pen1.

You also know that $2.50 per pen2 times the number of pen2 is the amount spent on Pen2.

She spent a total of $50.

 

Step 2: Write an equation that represents the total dollar amount spent, using $3, $2.50, x, y, and $50.

Some help for setting up:

 

2.5y + 3x = 50      (this is your equation)

 

3x is the amount spent on x number of Pen1.

2.5y is the amount spent on y number of Pen2.

50 is the total amount spent.

 

Step 3: Solve for x (or y) for one of the equations. Then substitute it into the other equation.

Example:

 

(After solving for x in equation 1:) 

 

         x = ?

               |

               |

               V

2.5y + 3*(?) = 50

 

Solve for y. Hooray, now you know y. Plug the answer of y into equation 1 and solve for x.