Y=x+5 find the slope of a line perpendicular to each given line

The given dot plot represents the average daily temperatures, in degrees fahrenheit, recorded in a town during the first 15 days of september. if the dot plot is converted to a box plot, the first quartile would be drawn at __ , and the third quartile would be drawn at __ link to graph: .

Can someone me out here and the tell me the greatest common factor

Could someone me with this question i’ve been stuck on it for 20 minutes