first note that if y = 2x, then x = y/2 .
hope you have made a sketch and know that this problem involves horizontal disks with respect to y.
for rotation about x = 1, your radius of revolution is a horizontal segment from the line x = 1 to the line x = y/2.
since x = 1 is to the right of x = y/2, the length of the radius is 1 - y/2.
so, your volume found by disks is ...
for rotation about x = 2, note that this will involve the washer method w/r to y.
your inner radius goes from x = 2 to x = 1 ... r = 2-1 = 1
your outer radius goes from x = 2 to x = y/2 ... R = 2 - y/2