7x+2y=11
-2x+3y=29
how do you solve this problem?

Average acceleration: i have no idea how to do this.

Ihave trouble finding the nth term of a linear sequence

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