Question

To solve the equation m-6=13 , you should:

subtract 13 from both sides.

subtract 19 from both sides.

add 6 to both sides.

add 13 to both sides.

Answer 1

add 6

Answer 2

You want m by itself on the left side because you want to have simply
m = some number as the solution.
Look at what is happening to m on the left side: 6 is being subtracted from it.
The opposite operation to subtraction is addition.
So since you have m - 6 on the left side and you want m by itself, you do the opposite, you add 6, but in an equation, whatever you do to one side of the equation, you must do to the other side, so you need to add 6 to the right side also.