How are the processes of adding monomials and adding polynomials alike? how are the processes different?

What situation is an example of an observational study

The border line of the linear inequality 4x + 7y < 5 is dotted true or false?

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