What is the constant proportionality of this problem

Find and simplify an expression for the area of five rows of x squares with side lengths of x centimeters.

Find the slope of the line passing through a pair of points

When you have 25 numbers, and jake picks 3 random numbers and puts them back, what is the chance bob has of picking those 3 numbers when he picks 6 random numbers (without putting them back)? explain.