Which equation represents the hyperbola shown in the graph?

Which equation represents the partial sum of the geometric series?

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

The difference of two numbers is 40. find the numbers if 0.3 parts of one number is equal to 37.5% of the other one.