The correct answer is 2.
Step 1: in order to solve an equation, you need to isolate the variable. Meaning, you need to get it by itself In this case, the variable is c. So, what you will do is subtract 20 on both sides of the equation and you should end up with 10c=20.
Step 2: We still need to get c by itself so, we have to do the inverse operation of multiplication, which is division. We then divide 10 on both sides of the equation. The answer you should come up with is c=20
Hope this helps! Have a great day/night:)