Well, your statement is the following:
In case x statisfies the equation "4+3+2=x+2" then x must be equal to 7.
But your statement does not state: 7 is a solution to the equation "4+3+2=x+2"; in symbols this statement would be: x=7 => 4+3+2=x+2
This is why the equivalence signs "<=>" are essential. Without them you do not make the statement that 7 is a solution and is the only solution to the equation.
Even more, it is actually the "<=" direction which is the most important one. If you are only asked to find SOME solution to the equation, then it is enough to show that "x=7 => 4+3+2=x+2". So in your answer you have actually left out the essential answer of the task.
Sometimes when I try to tell this to my students they seem not willing to try to understand this. Well, it might be picky, but then as soon as it comes to more complicated mathematical proofs it becomes very important in which direction the implication signs go and the argument "you should just put in the implication signs such that it is right and give me at least some points" doesn't work anymore.