One can ask about the time *until* a child first asks ``Are
we there yet?''. This is different from the time *at which* a
child first asks. This is given by subtracting the current time from
both sides of the previous equation. The result is

where

is the time from now

*until*a child first asks ``Are we there yet?''is the time

*since*we left (the house)*C*is the number of children in the car*A*is the number of activitiesand

Dwight Barkley 2006-07-25