Part of the properties of equality are known as inverse operations, meaning we can reverse certain terms in a problem by doing their opposite. For example, the opposite of +11 in your problem is -11. To remain equal, the operation must be done on both sides, so we would also need to subtract 11 from the 1 on the other side of the problem. Below is the full solution to the problem.
5x + 11 = 1
Subtract 11 from both sides.
5x = -10
The opposite of multiplication is division, so we need to divide both sides by 5.
x = -10/5
So, the answer is -10/5 unsimplified. This simplifies down to -2.
