The interior angle of the polygon is given by,
( (x-2) /x ) * 180
Let us take the sides as a and 2a.
substituting in the above formula, we get
((a-2)/a ) *180 / ((2a-2)/2a ) *180 = 3/4
(a-2)/a * 2/(a-1) = 3/4
(a-2) / (a-1) = 3/4
4a-8 = 3a-3
⇒ a=5
Therefore the sides are 5 and 10.