How do you know if lines are perpendicular?

Given a(-12,5) and b(12,29) find the point that divides the line segment ab three-eighths of the way from a to b

Leo is going to use a random number generator 4 0 0 400 times. each time he uses it, he will get a 1 , 2 , 3 , 4 , 1,2,3,4, or 5 5. what is the best prediction for the number of times that leo will get an odd number?

What is the range for 31,39,29,34,37,24,36,33,34,28