SOLUTION: alice is counting a cash register at the end of the night. he has $1015 in $5 bills and $10 bills. if she has 138 bills all together, how many of each type does she have?

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Question 956793: alice is counting a cash register at the end of the night. he has $1015 in $5 bills and $10 bills. if she has 138 bills all together, how many of each type does she have?
Answer by addingup(3677) About Me  (Show Source):
You can put this solution on YOUR website!
Let's call the $5 a and the tens b
a+b= 138 (equation 1), and therefore a= 138-b
5a+10b= 1015 (equation 2) Now, in this equation we substitute the value of a, since we just said that a= 138-b:
5(138-b)+10b= 1015
690-5b+10b= 1015
690+5b= 1015
5b= 325
b= 325/5
b= 65, and since we said that a= 138-b:
a= 138-65 = 73
Check: (65 x 10) + (73 x 5)= 650 + 365= 1015 Correct.