What is the ratio equivalent to 21: 9?

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

What numbers are included in the set of integers? what numbers are not included?

Prove that the value of the expression 7^8–7^7+7^6 is divisible by 43.