<p>Suppose the elements X and Y combine to form two compounds&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>X</mi><msub><mi>Y</mi><mn>2</mn></msub><mo>&#160;</mo><mi>a</mi><mi>n</mi><mi>d</mi><mo>&#160;</mo><msub><mi>X</mi><mn>3</mn></msub><msub><mi>Y</mi><mn>2</mn></msub></math>. When 0.1 mole of&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>X</mi><msub><mi>Y</mi><mn>2</mn></msub></math>&nbsp;weighs 10g and 0.05 mole of&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>X</mi><mn>3</mn></msub><msub><mi>Y</mi><mn>2</mn></msub></math>&nbsp;weighs 9g, the atomic weights of X and Y are:</p>