If $4u-5v=23$ and $2u+4v=-8$, find the value of $u+v$.
4u - 5v = 23
2u + 4v = -8
Then 4u + 8v = -16. Therefore, 3v = 39, and v = 13. Subsituting, we get that u = 22, so u + v = 22 + 13 = 35.
