To solve the equation [tex]\(5x + 3 = 28\)[/tex], you should follow these steps to isolate the variable [tex]\(x\)[/tex]:
1. The first operation to be done is to subtract 3 from both sides of the equation. This is to remove the constant term that is not associated with the variable [tex]\(x\)[/tex].
Therefore, the correct operation to perform first is:
Subtract 3