Test has been due for awhile now. Needs to get done

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?

Amovie streaming service charges it’s customers $15 a month. martina has $98 saved up. will she have any money left over if she pays for the maximum amount of months she can afford? explain.

What is the domain of the step function f(x)=[2x]-1?