What is the ground-source voltage of this current mirror?

In Neamen’s microelectronic book, there’s a problem using this current mirror

There is a 5V DC voltage source above the current source.
The reference current is 250 microAmp.
The threshold voltage is 1V.
The transistors are matching (W/L is 3 for both).
The Kn’ is 80 microAmp/volts squared.

Also, Instead of ground, there’s a -5V DC voltage.

What is the VGS of the two transistors?

from the figure, it seems that the Vgs should be 10V. Since assuming there’s no voltage drop acroos the current source, V+ – V- = Vgs. However, getting the Vgs from the drain current equation

yields a 2.44V.

Which one is corrent and why?

EDIT: And no this is not a homework question.