D=R x T help

Question

Two trains leave Columbus simultaneously traveling on the same track in opposite directions at speeds of 50 and 73 mph. How long will it take before they are 430.5 miles apart

Answer 1

Hi Mae,

 

So you know d = rt

 

d₁ is the distance of the first train

r₁ is the speed of the first train = 50 mph

t₁ is the time of the first train

 

d₂ is the distance of the second train
r₂ is the speed of the second train = 73 mph
t₂ is the time of the second train

 

Now t₁ = t₂, so we can just use t without any subscripts

and d₁ + d₂ = 430.5 miles

 

Therefore r₁t + r₂t = 430.5

50t + 73t = 430.5

123t = 430.5

t = 3.5

 

The two trains will be 430.5 miles apart in 3.5 hours.