Finding the unknown atomic mass of element X

[maiad]

Homework Statement

Suppose a nameless element (X) was found to occur in three different substances (A, B and C). The relative molecular masses of A, B, and C were found to be 25.80, 43.70 and 83.50 respectively, compared to an assigned value of exactly 2.00 for H2. Subsequently, these substances were subjected to elemental analysis and were found to contain 92.3%, 81.7% and 85.6% of X respectively by mass.

What is the (likely) relative atomic mass of X, on this scale

The Attempt at a Solution

What i did was i found the molecular mass of element X in each substance being 23.8g ,35.7g and 71.7g respective. But I'm not sure what to do after this point. Any hints?

 

[mfb]

What would be the mass, if you knew that substance A would contain exactly one atom of X per molecule? How would all allowed values (for 1, 2, 3, ... atoms per molecule) look like in that case?
If that assumption gives results which do not fit to your other values, how can you fix it?