Answer:
B and D
Step-by-step explanation:
quadrilaterals only have 4 sides hence the prefix quad
So, when doing this kind of problems, the first thing that we would want to do is to add up (all) the numbers first, and by doing this, it would look like the following:

Then, we would then divide it by how many numbers they are.

Your answer:
7
Answer: n=-9
Step-by-step explanation:
We know:x^2+y^2+x−6y+9=0So, we complete the square as such:x^2+y^2+x−6y+9=x^2+x+y^2−6y+9=(x+1/2)^2+(y−3)^2=(1/2)^2=1/4
The perimeter of an object is found by adding all of the sides. The sides of his frame would be 2 ft, 2 ft, 1.5 ft (18 inches / 12 inches per foot = 1.5 feet), 1.5 feet. Adding these together we get a total length of 7 feet. However, he may want to use a slightly longer board to account for any errors!