For this question, all you have to do is subtract 6 from 10 to get 4. 4 + 6 is 10. z = 4.
Annabelle could arrange her blocks in one row of 42 building blocks as 1 times 42 = 42.
She could also arrange her blocks in 2 rows of 21 blocks because 2 times 21 is also 42.
The expression you want to simplify is 0-(x-y).
0-(x-y)
=-(x-y)
=-x+y
You just have to treat the negative sign in front of (x-y) as a -1 and distribute it to both x and -y.
