Anyone got the answers?

How do you use the elimination method for this question? explain, because i really want to understand!

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 quotient? x+5/ 3x²+4x+5 © 3x2 – 11 + x + s 3x – 11 + 60 x + 5 o 3x2 - 11 - 50 x + 5 3x – 11 - - x + 5