Answer
$45cm, 2.2diopters$
Work Step by Step
The focal length can be determined as
$f=(\frac{1}{d_{\circ}}-\frac{1}{d_i})^{-1}$
We plug in the known values to obtain:
$f=(\frac{1}{25-2.0}+\frac{1}{-(49-2.0)})^{-1}=45cm$
The refractive power can be determined as
$refractive power=\frac{1}{f}$
$refractive power=\frac{1}{45cm}=\frac{1}{0.45m}=2.2diopters$