Which equation should you solve to find x?

The sum of two numbers is 86, and their difference is 20. find the two numbers

Find the roots of the equation below. x^2 - 6 + 9 = 0

10 ! a train starts from grand city and travels toward belleville 388 miles away. at the same time, a train starts from belleville and runs at the rate of 47 miles per hour toward grand city. they pass each other 4 hours later. find the rate of the train from grand city.