You want to find the unit rate...
1350 divided by 8 = 168.75 if its asking for an estimate it will be 169
The 1st side is 13 yards, the 2nd is 18 yards, and the 3rd is 11 yards
To make it easier to graph this equation, you can manipulate it to get it in slope-intercept form. You'd do that like so:
7x + y = -7
y = -7x - 7
Now I can graph a bit more easily as I can more readily make out the slope and the y-intercept...