1. A concert charges $8.25 for youth tickets and $12.50 for adult tickets. If y is the number of youth tickets sold and a is the number of adult tickets sold, which of the following expresses, in dollars, the total revenue from the tickets sold? A) 8.25a+12.50y
B) 12.50a+8.25y
C) 20.75a+20.75y
D) 20.75(a+y)
Show work please.

Simplify 15(x - 4)(x -1)-3(x + 4)(x - 1) with steps

Suppose that 3% of all athletes are using the endurance-enhancing hormone epo (you should be able to simply compute the percentage of all athletes that are not using epo). for our purposes, a “positive” test result is one that indicates presence of epo in an athlete’s bloodstream. the probability of a positive result, given the presence of epo is .99. the probability of a negative result, when epo is not present, is .90. what is the probability that a randomly selected athlete tests positive for epo? 0.0297

Use matrices to solve this linear system: 5x1 − 2x2 = −30 2x1 − x2 = −13 x1 = x2 =