Answer:
81
Step-by-step explanation:
Given the expression: 
To make it a perfect square, we follow the following steps.
Divide the coefficient of x by 2
- Coefficient of x=18, 18/2=9
Square It
Add it to the expression
This is written as a perfect square as: 
The constant term required therefore is 81.
Answer:
You can go for 1x9, 2x8, 3x7, 4x6, 5x5.
5x5 is the best as it builds a square, which maximizes space.
20*2.50 = $50.
12 hours? If I'm wrong, sorry about that