Question 204080
Velocity  = distance  / Time  ,,,,or  t= d/v
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T1 -2 = T2
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150/v -2 = 150 /(v+20)
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mult  thru  by  v(v+20)
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150(v+20) -2(v)(v+20) = 150(v)
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150v +3000 -2v^2 -40v =150v
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-2v^2 -40v +3000 = 0
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v^2 +20v -1500 = 0
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(v+50)(v-30) = 0
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v= 30,  -50 ( not  realistic)
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check
150/30=5,,,150/(30+20) =3,,,,ok