1. The problem statement, all variables and given/known data Evlute the surface integral 2. Relevant equations f(x,y,z)=x+y+z where sigma is the parallelogram with parametric equations x=u+v, y=u-v and z=1+2u+v where 0 <=u<=2 and 0<=v<=1. 3. The attempt at a solution I have no idea how to tackle this. Any suggestions?