What is the explicit formula for the geometric sequence with this recursive formula?
(a1 = -3
an= a n-1 •(1/8)

Solve this system of equations. 12x − 18y = 27 4x − 6y = 10

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

3x + 4y = 5 x- 3y = -7 solve by substitution