Question 82838
3. 
a.  {{{(72 hr/1 * $4/1 hr)}}} [cancel out the hour units; the dollar units are left]
.
{{{(72 /1 * $4/1 )}}} 
$288/1 [multiply straight across
$288
.

b. {{{(55 mi/1 hr * 7 hr/1 day*1 day/24hr)}}}[convert days to hours]
[cancel out the units wherever possible (hours and days cancel out]
.
{{{(55 mi/1  * 7 /1 *1 /24hr)}}} [you are left with miles/hour]
16.0416 mi/hr    [multiply straight across]
.
 
c.  35 people/1 party * 2.5 pizzas/10 people [cancel units wherever possible (people units)]
.
35 /1 party * 2.5 pizzas/10
35 people/1 party * 2.5 pizzas/10 people 
8.75 pizzas/party  [multiply straight across]