Sam paid $8.28 for 18 stamps at this rate how much would it cost to buy 12 stamps

[tex]\bf \begin{array}{ccll} \$&stamps\\ \text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\ 8.28&18\\ x&12 \end{array}\implies \cfrac{8.28}{x}=\cfrac{18}{12}\implies \cfrac{8.28\cdot 12}{18}=x[/tex]