Resistance R = row * L / A of a conductor.
row = resistivity of the material and is a constant.
since I = current = V / R, if length is doubled, then R is doubled, so current becomes half.
If thickness (R) is doubled, then R becomes 1/4 th value. So the current becomes 4 times.
Current in W1 = Current in W2
As thickness of W2 is 2 times that of W1, and length of W2 is n times that of W1, then current in W2 will be 4 * I1 /n .
since both currents are same, n = 4. ie., length is 4 times that of W1.