Answer:
($8.09*s) + ($3.79*c)
$70.77
Explanation:
First lets start with the equation and how to get it. Now we know the cost for satin fabric, which is $8.09, and we know that the chosen variable is s. Since it is "per yard", we know we will be multiplying. So now we set it up
$8.09*s
Now lets start with the cotton fabric. We know that the cotton fabric costs $3.79, and the chosen variable is c. Once again, it is per yard so we are multiplying.
$3.79*c
We now have the equation for each fabric so now we can put it together.
$8.09*s + $3.79*c
And that is the final equation. If you want, you can add parenthesis to separate it more. This is optional ONLY since they are already separated by a "+"
($8.09*s) + ($3.79*c)