My math teacher wants us to prove that all of our answers are correct.

Question

But how am I supposed to be able to prove stuff, like this, for example.
The directions want you to write out the words in to an equation.
Seven is the sum of X and 5.
so my answer is 7= x +5
How would I prove my answer?

Answer 1

Doesn't x = 2? Substitute 2 for x.

Doesn't 7 + 2 = 7?

Answer 2

We're not supposed to figure out what the variable is.
The direction for the question was to write out the sentence in an equation

Answer 3

The question wants you to figure out what number replaces X.

7 = x + 5
7 = ? + 5.

What number replaces x, or the question-mark? You're going to write:

x = (some digit, which is your answer)

Proving is easy. Just write
7 = x + 5 down again, but this time replacing x with your answer.

Answer 4

Oh.

If it's any comfort, I have no idea how writing sentences embodying equations could be proven, either.