I need help with this one

Which equation results from adding the equations in this system? x+6y=9 and -x+2y=-15

The first side of a triangle measures 5 in less than the second side, the third side is 3 in more than the first side, and the perimeter is 17 in. how long is the third side? if s represents the length of the second side, which of the following represents the length of the third side? s-5 ws-2 s+ 3 next question ask for turn it in

Ellen makes and sells bookmarks. she graphs the number of bookmarks sold compared to the total money earned. why is the rate of change for the function graphed to the left?