2х + 3y = -6
—4х – бу = 12

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

:24% of students in a class are girls. if there are less than 30 students in this class, how many students are there? how many girls are there?

With number 11 ( show how you got the answer)