Anurse practitioner prepares an injection of promethazine, an antihistamine used to treat allergic rhinitis. if the stock bottle is labeled 30. mg/ml and the order is a dose of 15.0 mg , how many milliliters will the nurse draw up in the syringe?

Essentially what the question is asking you to find is the volume of promethazine the nurse will fill the syringe with.  The question gives you :
-  Density =  30 mg / mL
-  Mass    =  15.0 mg

Therefore you can solve using the formula:
    
                   =   
                   =    0.5 mL

The  grandmother cell  is a hypothetical  neuronthat represents a complex but specific concept or object.[1]  it activates when a person "sees, hears, or otherwise sensibly discriminates"[2]  a specific entity, such as his or her grandmother. the term was in use at least as early as 1966 amongst staff and students in the department of experimental psychology, university of cambridge, england. a similar concept, that of the  gnostic neuron, was proposed two years later