Jawapan

2016-05-09T18:44:47+08:00
I think its

s = 1/2 (u+v) + u
s = 1/2 u + 1/2 v + u
s - 1/2 v = 1/2 u + u
s - 1/2 v = 3/2 u
u = 2/3 s - 1/3 v