A Solid Is Bounded Below by the Triangle Z = $\ge$

Essay

A solid is bounded below by the triangle z = 0, x $\ge$ 0, y $\ge$ 0, x + y $\le$ 1 and above by the plane z = x + 6y + 2.If the density of the solid is given by $\delta$ (x, y, z)= z, find its mass.