Question 964014
________________rate____________time____________distance
train___________r________________t_______________U
plane___________r+k______________t_______________V


RT=D rate time distance relationship for rate, time, distance, uniform travel rates rule.


KNOWN:
U=80
V=280
k=100
UNKNOWN:
r, t.


{{{system(rt=U,(r+k)t=V)}}}


{{{t=U/r}}}
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{{{r+k=V/t}}}
{{{r+k=V/(U/r)}}}
{{{r+k=Vr/U}}}
{{{highlight(r=Vr/U-k)}}}------solution formula for r, the rate for the train.
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Substitute the given values to evaluate r.