Question 236706
Vince left trout creek driving at 40km/h. Sybil followed 2h later driving at 50km/h. How far down the road will Sybil overtake Vince? 
Also to solve it, it must either be the substitution or elimination method. 
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Vince DATA:
rate = 40 km/h ; distance = v km ; time = d/r = v/40 hrs.
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Sybil DATA:
rate = 50 km/h ; distance = s km ; time = d/r = s/50 hrs.
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Equations:
vince time - sybil time = 2 hrs
v/40 - s/50 = 2
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vince distance = sybil distance
v = s
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Substitute for "v" and solve for "s":
s/40 -s/50 = 2
50s - 40s = 2*40*50
10s = 80*50
s = 400 km (distance sybil will have to drive to overtake vince)
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Cheers,
Stan H.