SOLUTION: Anna has 12 bills in her wallet, some $5 and some $10. The total value of the bills is $100. How many of each bill does Anna have?

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Question 49368: Anna has 12 bills in her wallet, some $5 and some $10. The total value of the bills is $100. How many of each bill does Anna have?
Answer by aaaaaaaa(138) About Me  (Show Source):
You can put this solution on YOUR website!
number of $5 bills = x
number of $10 bills = y

We conclude that:

value of $5 bills = 5x
value of $10 bills = 10y

Therefore:

system%285x+%2B+10y+=+100%2C+x+%2B+y+=+12%29

Solved by pluggable solver: SOLVE linear system by SUBSTITUTION
Solve:
+system%28+%0D%0A++++5%5Cx+%2B+10%5Cy+=+100%2C%0D%0A++++1%5Cx+%2B+1%5Cy+=+12+%29%0D%0A++We'll use substitution. After moving 10*y to the right, we get:
5%2Ax+=+100+-+10%2Ay, or x+=+100%2F5+-+10%2Ay%2F5. Substitute that
into another equation:
1%2A%28100%2F5+-+10%2Ay%2F5%29+%2B+1%5Cy+=+12 and simplify: So, we know that y=8. Since x+=+100%2F5+-+10%2Ay%2F5, x=4.

Answer: system%28+x=4%2C+y=8+%29.