Step-by-step 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