Write the sum of the numbers as the product of their gcf and another sum 58+14

What is the rescursive formula for this geometric sequence? 7, -14, 28, -56

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

Complete the solution of the equation. find the value of y when x equals to 6 4x+y=20