Answer
The dimensions are d-2 by d+9, where both dimensions must be greater than 0.
Work Step by Step
You are given $d^{2}$-7d-18. Factor it out:
$d^{2}$+2d-9d-18 -break out the middle value-
($d^{2}$+2d)+(-9d-18) -group the first two and last two terms-
d(d+2)-9(d+2) -Find the GCF of each grouping-
(d+2)(d-9) -factor out the common term-
=(d+2)(d-9)
