Please explain the second step where Vx = ... and Vy = .... Idon't understand why it's (0 - x)/2 . Is this a specific conceptwith a title that I'm forgetting? Thank you for your help!

1. A United Airlines plane is flying in a straight line towards a control tower with a speed of 250 mi/hour. At time t = 0 it is located 300 mi East and 400 mi South of the control tower. Use a coordinate system with the origin at the control tower. (a) Find the parametric equations of motion for the United Airlines plane. d = - 300+(-400)? = soo (300, -400) UA plane reaches control tover et t= soo=2 250 300 -15o -1-600) 200 - Vx 2 2 parametric equations are : X ( 300 150 t -400 + 200 t y =