Me i beg i really need with this problem!

Area = length x width

x² + 12x = l * x

A.  

First, you factor x from x² + 12x



area = x (x+12)

area = (x+12) * x

Length = x + 12

B.

If x = 10,
l = x + 12 = 10 +12 = 22
length = 22
and
Area = x² + 12x = 10² + 12(10) = 100 + 120 = 220
area = 220
        

Hope this helps :)