Because we’re given 4 Ws and told that they add to 20, we can simply divide 20 by 4 to find that each W value is equal to 5 (5+5+5+5=20).
We can then use our new found information for w+w+x+x = 24. We know that W = 5, so: 5+5+x+x = 24, and then 10+2x (because there were two Xs (if it was x+x+x, it would be 3x)) so, 10+2x=24, we can subtract 10 from both sides to get 2x by itself:
2x=24-10,
2x=14,
Then to get X by itself, we can divide by 2 on both sides:
2x/2 = 14/2
x=7
So now we know X’s value, X=7