If 4u-5v=23 and 2u+4v=-8+4u, find the value of u+v.
4u - 5v = 23 (1)
2u + 4v = -8 + 4u → u + 2v = -4 + 2u → 2v + 4 = u (2)
Sub (2) into (1)
4 ( 2v + 4) - 5v = 23
8v + 16 - 5v = 23
3v = 23 - 16
3v = 7
v = 7/3 and 2 (7/3) + 4 = u = 26/3
u + v = 26/3 + 7/3 = 33/3 = 11