Question 266535
This is similar to an RTD question. we get
person . . . . . .rate . . . . . . .time . . . . . . distance
mary . . . . . . . .2r . . . . . . . .1/(6r) . . . . . . 1/3 = 0.33333
bob . . . . . . . . .r  . . . . . . . .
billy . . . . . . . .(0.8r) . . . . .  1/(6r) . . . . . . 2/15 = 0.13333333
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Billy runs 2/15 of a mile