A^2-2ab+b^2=(a-b)^2
(a-b)^2- c^2= (a-b-c)(a-b+c)
[difference of square]
Hope this can help.
<span>With five houses every three hours, Brianna will paint 20 houses in 12 hours. 12 hours / 3 hours = 4 'rounds'. 5 houses * 4 rounds = 20 houses.
With three houses every four hours, Nicholas will paint 9 houses in 12 hours. 12 hours / 4 hours = 3 'rounds'. 3 houses * 3 rounds = 9 houses.
So Brianna will paint 20 - 9 more houses than Nicholas, or 11 houses more.</span>
We can solve this using the FOIL method.
= (7x + 3)(7x - 3)
= (7x * 7x) + (7x * -3) + (3 * 7x) + (3 * -3)
= 49x - 21x + 21x - 9
= 49x - 9
Hope This Helped! Good Luck!
I agree with B because it sounds like it fits in there better than any others