There are 5 red marbles, 15 blue marbles, and 5 green marbles in a bag. if you reach in and randomly draw two marbles without replacing the first, what is the probability that both will be blue?

Can you draw an isosceles triangle with only one 80 degree angle?

Aschool typically sells 500 yearbooks each year for 50 dollars each. the economic calls does a project and discovers that they can sell 100 more yearbooks for every $5 decrease in price. the revenue for yearbook sales is equal to the number of yearbooks sold times the price of the yearbook. let x represent the number of $5 decrease in price. if the expression that represents the revenue is written in the form r(x)=(500+ax)(50-bx). to maximize profit, what price should the school charge for the yearbooks? what is the possible maximum revenue? if the school attains the maximum revenue, how many yearbooks will they sell?

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?