If a tadalafil 10mg/tab has a typical half life of 17.5 hours, how long will it take until the blood concentration of this dosage falls to 25% of its initial strength?
a. 70 hours. b. 52.5 hours. c. 35 hours. d. 17.5 hours.

Which is the completely factored from of xy^3-x^3y

Lance lived in portugal and brazil for a total of 14 months to learn portuguese. he learned an average of 130 new words per month when he lived in portugal, and an average of 150 new words per month when he lived in brazil. in total he learned 1920 new words. write a system of equations to represent the situation. use x to represent portugal, and y to represent brazil

Tickets to a science exposition cost $5.75 each for studentd and $7.00 for adults.how many students and adults went if the ticket charge was $42.75