Hey there!
Since the given equation is subtracting, we're going to do the opposite of s traction which addition; whereas addition opposite is subtraction, division is multiplication, and multiplication is division. Now that we got that information out the way, we can finally answer your question
The very first step to solving c - 7 = 13 is ADDING 7 to BOTH SIDES because it is the opposite of subtracting
Answer you're looking for: Option A. Add 7 to both sides of the equation
Good luck on your assignment and enjoy your day!
~Amphitrite1040:)