Assuming this relationship is directly proportional, we know there is a unit rate. Since we know Carla earns $84 for 7 hours of babysitting, we can find the unit rate through division:
$84 earned / 7 hours = $12 per hour
We now know Carla earns $12 per hour. Given this information, we can multiply the unit rate by 8 hours to identify how much money Carla will have earned after 8 hours:
$12 per hour • 8 hours of babysitting = $96 after 8 hours
Final answer: After a total of 8 hours of babysitting, Carla will have earned $96.