Let the three numbers be represented by x, y, and z in the order of 1st, 2nd, and 3rd. Therefore, we can write:

y=x-1 ("The second of the three numbers is 1 less than the first.")

z=y-5 ("The third number is 5 less than the second")

x=2z (" the first number is twice as large as the third")

Using Algebrator to solve for x, y, and z, we get:

x=12

y=11

z=6