college algbra

Question

n? Monday, Harold picked up two

donuts and three

large coffees for the office staff. He paid $ 3.62 .
  
On? Tuesday, Melinda picked up four

donuts and two

large coffees for the office staff. She paid $ 4.12 .
  
What is the cost of one? donut? What is the cost of one large? coffee?

Answer 1

Hi Holly, 

Step One: Define our terms

D means "donut"

C means "coffee"

Step Two: Create our equations

Monday: 2D+3C=3.62

Tuesday: 4D+2C=4.12

Step Three: Solve for D

2D=3.62-3C

D=1.81-1.5C

Step Four: Solve for C 

4D+2C=4.12

4(1.81-1.5C)+2C=4.12

7.24-6C+2C=4.12

7.24-4.12=6C-2C

3.12=4C

0.78=C

Step Five: Find the cost

2D+3(.78)=3.62

2D=1.28

D=0.64

∴A donut costs $0.64 while a large coffee costs $0.78.

Sincerely, 

Starlyte H.