Question

Jan buys 12 pens for 10$. Each pen costs the same amount of money. Write a proportion to find the number of pens Jan can buy $15. Then solve your proportion for the number of pens.

Answer 1

You can write the proportion as 2 equal fractions or as two equal ratios.

`(12)/(10) = (x)/(15)` or 12 pens:$10 = x pens:$15

You can buy x pens for 15 dollars. One way to find x is by cross multiplying the fractions.

10x=12×15
10x=180
----- -----
10 10
x=18

You can buy 18 pens for $15.