Answer:
The proposed equation is solved as follows:
2X + 7 = 21
2X = 21 - 7
2X = 14
X = 14 / 2
X = 7
The value of X is 7.
A first degree equation is an algebraic equation in which each term is either a constant or a product of a fixed term on a single variable. Therefore, this equation is a first degree one, since it only has a single variable, which is X.