Question

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

Answer 1

`\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`

Answer 2

There are two ways to solve this question. Choose the method that is easier for you.

METHOD 1
STEP 1:
find rate for one stamp
= $8.28/18
= $0.46 cost of one stamp

STEP 2:
multiply rate of one stamp by 12
= $0.46 * 12
= $5.52 cost of 12 stamps


METHOD 2
set up a ratio comparing the number of stamps to the price.

18/$8.28= 12/x
cross multiply
18x= (8.28)(12)
18x= $99.36
divide both sides by 18
x= $5.52


ANSWER: The cost of 12 stamps is $5.52.

Hope this helps! :)