Selective serotonin reuptake inhibitor. Selective serotonin reuptake inhibitors (SSRIs), also known as serotonin-specific reuptake inhibitors or serotonergic antidepressants,[1] are a class of drugs that are typically used as antidepressants in the treatment of major depressive disorder and anxiety disorders.
Then you're looking for the midpoint! The midpoint of a line segment is the point located midway between the endpoints of the line segment. This tutorial tells you about the midpoint of a line segment.
The midpoint method can be used if just two points on the demand curve are known. You do not need to know the function relating price and quantity demanded to use this method. The point elasticity captures the change in quantity demanded to a tiny change in price. To calculate the point elasticity, you must have a function for the relationship between price and quantity.