Solve the Problem $\delta ( x , y , z ) = x + y + z$

Multiple Choice

Solve the problem.
-Find the mass of a tetrahedron of density $\delta ( x , y , z ) = x + y + z$ bounded by the coordinate planes and the plane $\frac { x } { 8 } + \frac { y } { 5 } + \frac { z } { 4 } = 1$

A) $\frac { 1360 } { 9 }$
B) 136
C) $\frac { 544 } { 3 }$
D) $\frac { 340 } { 3 }$