Aline with a positive slope and a line with a negative slope are parallel. sometimes always or never?

Y=4x^2+x-1 solve using quadratic formula

Expresa commuter train leaves downtown sation and travels at a average speed of 55 miles per hour towards the north side sation, which is 50miles away. thirty minutes later, express commuter train #7 leaves north side and travels at a average speed of 35miles per hour towards downtown sation. at the moment the two trains pass each other, how far(in miles) is train #12 from the downtown sation and how long(in minutes) has the #12 train been traveling

What is the solution to this system of equations? y= 2x - 3.5 x - 2y = -14