Please help! 50 points An algebra class has 21 students who all participate in a welcome activity introducing themselves to each other in pairs. One student wants to know how many introductions were made.

Fill in the values of n and r to complete the formula for finding the number of combinations of introductions.

(urgent ) use pi 3.14 to estimate the circumference of the circle to the nearest hundredth middle is 4in (urgent )

An equation representing lyle’s hedge-trimming business is a = 12n - 300 where a is the amount of profit or loss in dollars and n is the number of hedges trimmed. how would the graph of lyle’s business change if the equation a = 10n - 300 represented his business? the graph would be flatter. the graph would be steeper. the graph would start closer to the origin. the graph would start lower on the y-axis.

Solve this system of equations. 12x − 18y = 27 4x − 6y = 10