Need ! what is the distance between points (-42, 63) and (-39, 67)

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 the chart is here

Math it's appreciated. (picture provided)

15m is what percent of 60m; 3m; 30m; 1.5 km? the last one is km not m