Well this is just a nightmare and I got my first C on an exam in college after a year, going to finish calculus III with triple integrals and I can't figure this out at all

the region is:

Q: { (x,y,z) : x: [0,1] y: [0,x] and z: [0,3] }

How do I find the boundaries of z? I can set up the integrals dzdxdy, dzdydx, I can also draw the region, I get the idea in 2d but I don't get how the bounds of integration for x are from 1 to y. How??