A motel clerk counts his $1 and $10 bills at the end of the day. He finds that he has a total of 48 bills having a combined monetary value of $138. How to find the number of bills of each denomination that he has?
Gael Woodward
Answered question
2023-01-01
A motel clerk counts his $1 and $10 bills at the end of the day. He finds that he has a total of 48 bills having a combined monetary value of $138. How to find the number of bills of each denomination that he has?
Answer & Explanation
bagosiwp2
Beginner2023-01-02Added 16 answers
First: Let's call the number of $1 bills: s Let's call the number of $10 bills: t Using the data in the problem, we can then create the following two equations: Given that we know the motel clerk has a total of 48 bills: Equation 1: \(\displaystyle{s}+{t}={48}\) We also know the 48 bills add up to $138, then: Equation 2: \(\displaystyle\${1}{s}+\${10}{t}=\${138}\) Step 1) The first equation for s must be solved: \(\displaystyle{s}+{t}-{\color{red}{{t}}}={48}-{\color{red}{{t}}}\) \(\displaystyle{s}+{0}={48}-{t}\) \(\displaystyle{s}={48}-{t}\) Step 2) In the second equation, swap out (48-t) for s, and then solve for t: \(\displaystyle\${1}{s}+\${10}{t}=\${138}\) becomes: \(\displaystyle\${1}{\left({48}-{t}\right)}+\${10}{t}=\${138}\) \(\displaystyle{\left(\${1}\cdot{48}\right)}-{\left(\${1}\cdot{t}\right)}+\${10}{t}=\${138}\) \(\displaystyle\${48}-\${1}{t}+\${10}{t}=\${138}\) \(\displaystyle\${48}+{\left(-\${1}+\${10}\right)}{t}=\${138}\) \(\displaystyle\${48}+\${9}{t}=\${138}\) \(\displaystyle\${48}-{\color{red}{\${48}}}+\${9}{t}=\${138}-{\color{red}{\${48}}}\) \(\displaystyle{0}+\${9}{t}=\${90}\) \(\displaystyle\${9}{t}=\${90}\) \(\displaystyle\frac{{\${9}{t}}}{{\color{red}{\${9}}}}=\frac{{\${90}}}{{\color{red}{\${9}}}}\) \(\displaystyle\frac{{{\color{red}{\cancel{{{\color{black}{\${9}}}}}}}{t}}}{\cancel{{{\color{red}{\${9}}}}}}=\frac{{{\color{red}{\cancel{{{\color{black}{\$}}}}}}{\color{red}{\cancel{{{\color{black}{{90}}}}}}}{10}}}{{\color{red}{{\color{black}{\cancel{{{\color{red}{\$}}}}}}{\color{black}{\cancel{{{\color{red}{{9}}}}}}}}}}\) \(\displaystyle{t}={10}\) Step 3) Substitute 10 for t in the solution to the first equation at the end of Step 1 and calculate s: \(\displaystyle{s}={48}-{t}\) becomes: \(\displaystyle{s}={48}-{10}\) \(\displaystyle{s}={38}\) The motel clerk had 38 $1 bills and 10 $10 bills.