What number should be added by both sides of the equation to complete the the square? x^2-10x=7

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?

The table shows the age and finish time of ten runners in a half marathon. identify the outlier in this data set. drag into the table the ordered pair of the outlier and a reason why that point is an outlier.

How do i put 3(x+7) in distributive property