Answer
(a) $2.47 * 10^{-7}m$
(b) $67.6 Å$
Work Step by Step
(a) recall that nano- means $10^{-9}$
$247nm *\dfrac{10^{-9}m}{1nm}$
$247 * 10^{-9}m$
$2.47 * 10^{-7}m$
(b) Recall that $p$ (pico-) means $10^{-12}$ and 1Å (Angstrom) equals $10^{-10}m$
$6760pm* \dfrac{10^{-12}m}{1 pm}*\dfrac{1Å}{10^{-10}m}$
$6760 *10^ {−12} * 10^{10} Å$
$6760 *10^{2} Å$
$67.6 Å$