How to determine if a side length represents a right triangle?

Three times the difference of federico’s age, and 4, increased by 7, is greater than 37. what are possible values of federico’s age?

If f(x)= 3x+6 which of the following is the inverse of f(x)

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?