How do I go about solving this problem?

Cindy has 2 boxes of pencils. Patrice has 5 boxes of pencils. Each box has the same number of pencils in it. Write an expression for the total number of pencils the girls have altogether. Then simplify it to create an equivalent expression.

Abag contains 3 red marbles 4 white marbles and 5 blue marbles if one marble is drawn from the bag what is the probability that the marble will be blue

Monica build a remote control toy airplane for science project to test the plane she launched it from the top of a building the plane travel a horizontal distance of 50 feet before landing on the ground a quadratic function which models the height of the plane in feet relative to the ground at a horizontal distance of x feet from the building is shown

Explain how you can use the associative property to evaluate (7x50)x4.