X + 30% = 74. How to find X?

Question

Mathematics

Good day everyone
. I know that this is a school math problem, but I can’t remember or google the rule by which it must be solved.

X + 30% = 74; x = ???

If you decide as 74 - 30% = 51.8, however 51.8 + 30% = 67.34, not equal to 74.

Please give me a link or the name of the rule or at least some clue, because I've been stupid on this for half an hour ...

Answer 1

100% = one = integer = 100 / 100 = 1.
X is 100% or 1 * X
30% of X is X * 30 / 100or 0.3 * X

1 * X + 0.3 * X = 1.3 * X = 74

X = 74 / 1.3 = 56.923