How do you know when to use the subtraction property of equality as a reason as opposed to subtraction of real numbers?

Subtraction property of equality is used when u have 2 sides with an equal sign in the middle and u want to subtract from both sides.
Example :
2x + 3 = 7 subtract 3 from both sides
2x + 3 - 3 = 7 - 3
2x = 4
x = 4/2
x = 2
When subtracting real numbers..if the numbers are on the same side of the equal sign...u can just subtract on that one side
Example :
2x = 7 - 3
2x = 4
x = 4/2
x = 2