$\begin{cases}X:R_1(OH)_a \\Y:R_2(OH)_b \end{cases}\Rightarrow \begin{cases}0,015a+0,02b=\frac{2.1,008}{22,4} \\0,02a+0,015b=\frac{2.0,952}{22,4} \end{cases}\Rightarrow \begin{cases}a=2 \\b=3 \end{cases}$$\Rightarrow \begin{cases}X:C_nH_{2n+2}O_2:0,015 mol \\Y:C_mH_{2m+2}O_3:0,02 mol \end{cases}\Rightarrow m_{CO_2}+m_{H_2O}=6,21$
$\Rightarrow 44(0,015n+0,02m)+18[0,015(n+1)+0,02(m+1)]=6,21$
$\Rightarrow 1,5n+2m=9\Rightarrow \begin{cases}n=2 \\m=3 \end{cases}\Rightarrow \begin{cases}X:HO-CH_2-CH_2-OH \\Y:HO-CH_2-CHOH-CH_2-OH \end{cases}$