Two cars are parked beside each other, facing in opposite directions. Car 1 accelerates at 5m/s^2 up to a max. speed of 25m/s, and Car 2 accelerates at 4m/s^2 up to a max. speed of 24m/s. How much time has elapsed when the cars are 200m apart?

2. Relevant equations

v=d/t

vf^2=vi^2+2ad

vf=vi+at

3. The attempt at a solution

Car 2

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576=8d

d=72m

it takes car 2 6seconds to travel 72m

Car1

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625=10d

d=62.5m

it takes car 1 5seconds to travel 62.5m

So, the cars are 134.5m apart at this stage. They need to travel 200m-134.5m=65.5m before they are 200m apart, yes? The answer is 6.83 seconds, but i don't understand how they got that. please help?