SOLUTION: On​ Monday, Harold picked up 4 donuts and 5 large coffees for the office staff. He paid 6.52  On​ Tuesday, Melinda picked up 5 donuts and 4 large coffees for the office st

Algebra ->  Equations -> SOLUTION: On​ Monday, Harold picked up 4 donuts and 5 large coffees for the office staff. He paid 6.52  On​ Tuesday, Melinda picked up 5 donuts and 4 large coffees for the office st      Log On


   

Question 1192913: On​ Monday, Harold picked up 4 donuts and 5 large coffees for the office staff. He paid 6.52  On​ Tuesday, Melinda picked up 5 donuts and 4 large coffees for the office staff. She paid 6.17  What is the cost of one​ donut? What is the cost of one large​ coffee?
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
On​ Monday, Harold picked up 4 donuts and 5 large coffees for the office staff. He paid 6.52  On​ Tuesday, Melinda picked up 5 donuts and 4 large coffees for the office staff. She paid 6.17  What is the cost of one​ donut? What is the cost of one large​ coffee?
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4D + 5C = 652
5D + 4C = 617
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Can you do the rest?
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1 way to do this is using elimination.
Multiply eqn 1 by 5 and eqn 2 by 4.
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4D + 5C = 652 times 5 ---> 20D + 25C = 3260
5D + 4C = 617 times 4 ---> 20D + 16C = 2468
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20D + 25C = 3260
20D + 16C = 2468
--------------------------- Subtract
9C = 792
C = 88
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Sub for C in any eqn to find D.