Answer
Please see the work below.
Work Step by Step
We know that
$10.0g BF_3\times \frac{1 mol \space BF_3}{67.81\space g\space BF_3}\times \frac{1\space mol \space BF_3: OR_2}{1 mol\space BF_3}\times \frac{141.93g BF_3:OR_2}{1 \space mol \space BF_3:OR_2}=20.93gBF_3:\space OR_2$