Answer:
[tex] \int\limits_R x \, dx \, dy [/tex]
Step-by-step explanation:
The z-coordinate can take any value between 0 and the value of the x-coordinate. On the other hand, the values of x and y are limited by those of the solid. We can summarize the volume of the solid with the following integral:
[tex]\int\limits_R\int\limits_0^x {1} \, dz \, dx \, dy = \int\limits_R x \, dx \, dy[/tex]