Explanation:
Lets break this word problem down:
"The difference" means we're going to be finding x - y ("difference" means we're finding how much one value "differs" from the other)
"a number and it's opposite" so we're doing x - y, where y = -x. So already, we can re-write this as x - (-x) or x + x
"is 28" so x + x = 28 ("is" always means "equals")
"Find the number" so we're finding x.
x - (-x) = 28 (I went back a step so I could write everything out more plainly)
simplify
x + x = 28
add
2x = 28
divide both sides by 2 to get x on its own
x = 14
Answer:
14