I need help with this

The sum of the speeds of two trains is 720.2 mph. if the speed of the first train is 7.8 mph faster than the second train, find the speeds of each.

Point s lies between points r and t on . if rt is 10 centimeters long, what is st? 2 centimeters 4 centimeters 6 centimeters 8 centimeters

If f(x) = 4x - 3 and g(x) = x + 4, find (f - g) (x)