You can put this solution on YOUR website! The world famous formula for this is D = RT.
Distance D=150 miles, Rate R=90 miles per hour. The unknown is T Time.
The equation D = RT becomes
150 = 90 T.
You must solve for T by dividing both sides by 90.
150/90 = T
T = 5/3 or 1.666 . . . hours.