I am thinking of a rectangle that has the two sides parallel to one another. Set the two functions equal to one another, so
9x-14=7x+4
After a bunch of algebra and math magic, 2x=18 => x=9
So if you just insert 9 into both equations, both will end up with a value of 67, so it ends up looking like a right triangle. Don't do that. Instead, to find the rectangle widths, use 9x-4 (+10 added to intercept) instead, while keeping 7x+4, so that the intercepts match.