ANSWER:
[tex]c=\frac{-13+f}{10-d}[/tex]
STEP-BY-STEP EXPLANATION:
We have the following equation:
[tex]10c-f=-13+cd[/tex]
To solve for c, we must express the equation such that c is alone on the left side of the equation, like this:
[tex]\begin{gathered} 10c-f+f-cd=-13+cd+f-cd \\ 10c-cd=-13+f \\ c\cdot(10-d)=-13+f \\ c=\frac{-13+f}{10-d} \end{gathered}[/tex]
