Answer :

To solve for C, you have to get both of the numbers with a C on the same side.  So, subtract the 5c from the right side onto the left side.

[tex]8c = 5c + 21\\8c - 5c = 5c - 5c + 21\\3c = 21[/tex]

Then, divide by 3 on each side.

[tex]3c = 21\\3c /3 = 21/3\\c = 7[/tex]

So, c = 7.
AL2006
That would be a simple linear equation in the variable 'c'. ... To find its solution, first subtract 5c from each side, then divide each side by 3 .