Hannah is helping her younger brother learn to count money. She gave her brother a total of 20
coins nickels and pennies. Hannah's brother said
he counted $0.68. How can Hannah solve a
system of equations to tell whether he counted
the money correctly?

Find an equation of the line perpendicular to the graph of 28x-7y=9 that passes through the point at (4,1)

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

The cost of a taxi ride includes an initial charge of $2.00. if a 5km ride cost $6.00 and a 10km ride cost $10.00, determine the cost of a 15km ride.