25-x=24+x

The game answer is 1, using Substitution you would find

25-1=24+1
24=25 that isn't true

25-x=24+x
Add x to both sides: 25-x+x=24+2x
25=24+2x
Take 24 away from both sides: 25-24=24+-24+2x
1=2x

Divide both sides by 2: .5=x

You can't enter decimals in, so it is wrong.

Also someone needs to go through and spell check the game. There are a bunch of misspelled words.