Question 972881
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distance=rate x time
Since distance is the same:
Carey's rate x Carey's time=Kristie's rate x (Carey's time - 40 seconds)
Let T=Carey's time
(10ft/s)(T)=(12ft/s)(T-40s)
(10ft/s)T=(12ft/s)T-480ft Subtract (12ft/s)T from each side.
(-2ft/s)T=-480ft Divide each side by (-2ft/sec)
T=240s Carey's time when both girls had run the same distance was 240 seconds.