Solve each system by addition, if possible

Having trouble understanding this.

x + y = 1

x - y = 7

Do I add it together like this:

x + y = 1

x - y = 7

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2x = 8

Then, should I divide it like this:

8/2x = 4

My professor at the college went too fast for me to understand how to do Solution by Eliminations.