Hello!

Ive been staring at this task for hours and would really appreciate if someone had a look at this:

Calculate:

∭ z dV
k

where k is the area which is limited by the surfaces :
x= 0
y= 0
z=0
x+y=1
x+y-z=0

I dont understand how the area looks and which "limits" to set!

Thanks in advance.