$\begin{cases}RCOOH:2x mol \\R_1OH:x mol\\RCOOR_1:y mol \end{cases}\Rightarrow \begin{cases}2x+y=0,2 mol (1) \\(R+67)(2x+y)=16,4 gam (2)\\(R_1+17)(x+y)=8,05 gam (3) \end{cases}$$\begin{cases}(1) \\(2) \end{cases}\Rightarrow R=15\Rightarrow R:CH_3\Rightarrow X:CH_3COOH$
$\begin{cases}(1) \\(3) \end{cases}\Rightarrow \begin{cases}0<x<0,1 mol \\ 0,1<x+y<0,2\\(R_1+17)(x+y)=8,05 gam \end{cases}\Rightarrow \frac{8,05}{0,2}<R_1+17<\frac{8,05}{0,1}$
$\Rightarrow 23,25<R_1<63,5$
$\Rightarrow R_1:C_2H_5-...???$