Steps:
18 x 2
What is that?
You can also think of it as 9 x 4 if that is easier
Then whatever you got for that, add 21 then subtract 12 and add 1
Is there any option to choose from ?
If so show them and I’ll probably be able to answer .
Since 16 and 25 are perfect squares you can factor the first part.
4^2-5^2(b+3)^2
=(4-5(b+3))(4+5(b+3))
=(4-5b-15)(4+5b+15)
=(-11-5b)(19+5b)
Which can be expanded if necessary,
= -209+150b-25b^2
The correct answer is 51156
Hope this helps :)