Do cars get better gas mileage with clean air filters? gas mileage for 10 cars with dirty air filters and clean air filters was studied. each car was tested with a clean air filter and once with a dirty air filter (with the order of the testing randomized). what type of study is this?

Aboat radioed a distress call to a coast guard station. at the time of the call, a vector a from the station to the boat had a magnitude of 45.0 km and was directed 15.0° east of north. a vector from the station to the point where the boat was later found is = 30.0 km, 15.0° north of east. what are the components of the vector from the point where the distress call was made to point where the boat was found? in other words, what are the components of vector c = b - a?