Im still confused on solving systems of equations can i get an overview

What is the measure of the smallest angle in the diagram? 15 29 32 45

Can someone check if i did this right since i really want to make sure it’s correct. if you do you so much

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