Question

Timothy has 72 coins, consisting of quarters, dimes, nickels, and 8 pennies. Samantha comes and takes all of his quarters, takes 3 of his dimes, takes 2 of his nickels, and leaves him with one penny, leaving him with 45 coins. What is the value of quarters that Samantha took?

Can someone explain how to solve this problem?

Answer 1

The total value of quarters that Samantha took is $3.75

Explanation:

Timothy has 72 coins.

He has:

Q quarters

D dimes

N nickels

8 pennies.

Then:

Q + D + N + 8 = 72

Samantha takes:

3 dimes

2 nickels

Leaves him with one penny, then she takes 7 pennies.

all of the quarters, so she took Q quarters.

So now Timothy has 45 coins.

And for each particular type of coin, Thimothy now has:

D - 3 dimes

0 quarters

1 penny

N - 2 nickels

And we know that he has 45 coins, then:

(N - 2) + 1 + ( D - 3) = 45

Which we can rewrite as:

N + D + 1 - 2 - 3 = 45

N + D - 4 = 45

N + D = 45 + 4 = 49

So we have two equations:

Q + D + N + 8 = 72

N + D = 49

Now we can replace the second equation into the first one:

(N + D) = 49

then:

Q + D + N + 8 = 72

Q + (D + N) + 8 = 72

Q + 49 + 8 = 72

Now we can solve this for Q

Q = 72 - 49 - 8 = 15

So Samantha took 15 quarters.

Each quarter has a value of $0.25

Then Samantha took:

15*$0.25 = $3.75

The total value of quarters that Samantha took is $3.75