Question

A child has a piggy bank that contains only quarters and dimes. Altogether, there are 27 coins in the bank and the total value of the coins is $4.50. How many quarters and how many dimes are in the piggy bank? I cant get the right answer no matter what I do

Answer 1

12 quarters 15 dimes how i know because quarters have 25 cents in them so i added 12 25 which equaled 300 and dimes have ten cents in them so i added 10 15 which equaled 150  so 300 +150 = 450

Answer 2

You can use a matrix equation to get the answer. You use these two equations: q+d=27 and 25q+10d=450. Alternatively you could use other methods to get the answer, but I like matrices. My 2 by 2 matrix is 1 1 I will refer to this equation as Matrix A. 25 10
My other matrix on the left side of the equals sign is: q This will be Matrix B.
d
On the right of the equals sign is this matrix: 27 This is Matrix C.
450
Taking the inverse of Matrix A, and multiplying it by Matrix C, you get what Matrix B equals: 12
15
In other words, there are 12 quarters, and 15 dimes. Hope that helps.