@Jeffrey_Marler , here is how to create a formula field that will format time in hours:
In your particular case, you may need to end up both fields, if you want them displayed on list view in weeks and days, also.
You could tweak the formula to divide the hours by 24 to give you the result in decimal days only. Or divide by 168 (24h x 7d) to give you the result in decimal weeks (but not weeks and days).