Could I have help with this? Please? 15 points!

The fence around a quadrilateral-shaped pasture is 3a^2+15a+9 long. three sides of the fence have the following lengths: 5a, 10a-2, a^2-7. what is the length of the fourth side of the fence?

Write the expression 7x^3-28xy^2 as the product of 3 factors

An ant travels at a constant rate of 30cm every 2 minutes. at what speed does the ant travel per minute