$7$ Steam undergoes a state change from $450C$ and $3\mathrm{.}5$MPa to $150C$ and $0\mathrm{.}3$MPa. Determine $H$ and $U$ using the following:

$($a$)$ Steam table data.

$($b$)$ Ideal gas assumptions. $($Be sure to use the ideal gas heat capacity for water.$)$