I need help with this problem

What is f(3) for the quadratic function f(x)= 2x^2+ + x - 12

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.

What is the solution to the equation? k/6.4=8.7 2.3 5.568 15.1 55.68