#### Answer

*graph is attached
Equation of line => $y= 248x+0.002$
At Absorbance=$0.635$
Concentration = $2.55*10^{-3}$$\frac{g}{L}$ = $2.55*10^{-3}$$\frac{mg}{mL}$

#### Work Step by Step

To get equation of line: Input the data into a Linear regression which will give you the equation of the line
To get Concentration at Absorbance of $0.635$:
The equation of the line is for a Absorbance vs Concentration $(g/L)$
Therefore we can input the $0.635$ into the equation of the line as $y$ and then we can solve for $x$
So... $0.635= 248x+.002$
$x= 2.55*10^{-3}\frac{g}{L}$
To get Concentration in $\frac{mg}{mL}$
$\frac{2.55*10^{-3}g}{L}*\frac{1000mg}{1g}*\frac{1L}{1000mL}=2.55*10^{-3}\frac{mg}{mL}$
Thus, Concentration = $2.55*10^{-3}$$\frac{g}{L}$ = $2.55*10^{-3}$$\frac{mg}{mL}$