If 7+ 5 is equal to 5 plus a number, what do you know about the number? why?

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

Omar is going on a road trip! the car rental company offers him two types of cars. each car has a fixed price, but he also needs to consider the cost of fuel. the first car costs $90 to rent, and because of its fuel consumption rate, there's an additional cost of s0.50 per kilometer driven.

Which word in the sentence below is an interrogative pronoun? who is picking us up from school? whousisfrom