I need to find the common difference can anyone help me?

Which is the equation of an ellipse with directrices at x = ±4 and foci at (2, 0) and (−2, 0)?

What is the value of x in the diagram below?

The swimming pool is open when the high temperature is higher than 20∘c. lainey tried to swim on monday and thursday (which was 3 days later). the pool was open on monday, but it was closed on thursday. the high temperature was 30∘c on monday, but decreased at a constant rate in the next 3 days. write an inequality to determine the rate of temperature decrease in degrees celsius per day, d, from monday to thursday.