Question 101076
Suppose you just have just enough dimes and quarters to pay for a loaf of bread and quart of milk, which cost $3.45. You have a total of 15 dimes and quarters. 
Let d = the number of dimes you have. 
Let q = the number of quarters you have. 
a. Write a system of equations that models the information given above.
Quantity EQUATION: d+q = 15
Value EQUATION:   10d + 35q = 345 cents
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b. Solve the system for the number of dimes and quarters you have. You may want to solve this by graphing.
It's easier to solve by elimination:
10d + 10q = 150
10d + 35q = 345
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Substract to get:25q = 195
q = 7.8
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Comment:
q should be a whole number.  Check your posting
to see if you have it correct.
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Cheers,
Stan H.