Answer:
Y=3x(x-4)
Step-by-step explanation:
If the rectangle has a fixed width of 300, it means that

where
and
are width and length, respetively.
So given the length
, the are would be

Answer:
4c - 2
Step-by-step explanation:
Add up all the terms to find the perimeter.
2c + 2(c - 1)
2c + 2c - 2
4c - 2
Therefore, the perimeter is 4c - 2.
21 hundreds would be 2100