The proportion that Alexandra can use to find r is 9 cups of water and 4 cups of dry rice
If Alexandra uses 12 cups of water and 6 cups of dry rice to make 18 cups of cooked rice, this can be expressed as:
[tex]\frac{12}{6} = 18cups[/tex]
To get the proportion "r" for the amount of dry rice to use to make 4 cups of cooked rice, we can write:
[tex]r = 4 cups[/tex]
Divide both expressions:
[tex]\dfrac{\frac{12}{6} }{\frac{a}{b} } =\frac{18}{4}\\\dfrac{12b}{6a}= \frac{18}{4}\\\dfrac{2b}{a} =\frac{18}{4}\\\frac{b}{a} =\frac{18}{8}\\\frac{b}{a} =\frac{9}{4} =r[/tex]
Hence the proportion that Alexandra can use to find r is 9 cups of water and 4 cups of dry rice
Learn more on proportions here: https://brainly.com/question/19994681
