Vy T. answered 02/08/15
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Let the number of dimes be d and number of nickles be n. You know that a dime is 10 cents or .10 of a dollar, a nickle is 5 cents or .05 of a dollar.
Set up:
The total number of coins is given to be 28
d+n=28
The total value of these 28 coins is $2.25
.10d+.05n=2.25
Solve:
With the first equation solve for n by subtracting d from both sides of the equation
n=28-d
Plug n=28-d into .10d+.05n=2.25
.10d+.05(28-d)=2.25
.10d+1.4-.05d=2.25
Combine like-terms by adding .10d with .05d
.05d+1.4=2.25
Subtracting both sides by 1.4
.05d = 2.25-1.4=0.85
Solve for d by dividing both sides by .05
d = 17
Find the number of nickles by plugging d=17 back into n=28-d
n=28-17=11
Answer: Number of dimes is 17 and nickles is 11
Check: Total number of coins (17+11) is 28
.10(17)+.05(11)=2.25