Irrational numbers are closed under subtraction true/false

If square root x = -7, then x= -49 true or false

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

Find the values of y: 3y^3(y^2+ 2/3y)=0