Can some one answer this for me.

Two technicians are discussing how to test a car's exhaust by holding a small piece of paper within an inch of the tailpipe mouth. technician a says that if the paper is vibrating due to a "puffing" output from the tailpipe, this signals a smoothly running engine. technician b says that if the paper is being drawn toward the tailpipe, this could indicate burned exhaust valves. who is correct? a. technician b b. both technicians a and b c. technician a d. neither technicians a or b

The graph shows the populations of two species over time. which type of symbiotic relationship does the graph represent? a. commensal b. mutualistic c. parasitic d. parent-offspring e. predator-prey

Trey has answered 15 e-mails. this is 20% of e-mails he must answer. how many e-mails does he need to answer? pls ; op'; ; p'[o; pio; uiylutryte