True or false: mathematical modeling involves creating equations that describe a system under investigation

Which is a reasonable estimate of the amount of water in a small, inflatable pool used by children?

What is a graph with a never ending line called?

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