To solve this problem you must apply the proccedure shown below:
1. You have that [tex] y [/tex] varies jointly as [tex] x [/tex] and [tex] z [/tex] and inversely as the product of [tex] w [/tex] and [tex] p [/tex]. Therefore, you can write the following equation, where [tex] k [/tex] is the constant of proportionality:
[tex] y=k(\frac{xz}{wp} ) [/tex]
2. Now, you must solve for the constant of proportionality, as following:
[tex] k=\frac{ywp}{xz} [/tex]
3. Susbtiute values:
[tex] y=\frac{7}{28} \\ x=7\\ z=4\\ w=7\\ p=8 [/tex]
[tex] k=\frac{(\frac{7}{28})(7)(8))}{(7)(4)} =0.5 [/tex]
4. Substitute the value of the constant of proportionality into the equation:
[tex] y=0.5(\frac{xz}{wp}) [/tex]
The answer is: [tex] y=0.5(\frac{xz}{wp}) [/tex]
