The total cost for Marky (TCM) is the cost of the bike plus the cost of the helmet:
[tex]\text{TCM}=114+18=132[/tex]And since the total cost for Marky is 120% the original cost for Holy (OCH), we can express it like this:
[tex]\begin{gathered} 120\text{\%}=\frac{TCM}{OCH}\times100\text{\%} \\ 120\text{\%}=\frac{132}{OCH}\times100\text{\%} \\ \end{gathered}[/tex]Solving for OCH, we get:
[tex]\begin{gathered} 120\text{\%}=\frac{132}{OCH}\times100\text{\%} \\ \frac{120\text{\%}}{100\text{\%}}=\frac{132}{OCH}\times\frac{100\text{\%}}{100\text{\%}} \\ 1.2=\frac{132}{\text{OCH}} \\ \text{OCH}\times1.2=132\frac{OCH}{\text{OCH}} \\ \text{OCH}\times1.2=132 \\ \text{OCH}=\frac{132}{1.2}=110 \end{gathered}[/tex]Then the original cost for Holy (OCH) is $110, and the total amount of money that Marky made is $132
