Question 1189377
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Helen starts when Antony has been driving for 15 minutes, or 1/4 hour.  At 72km/h, Antony travels 18km in that 1/4 hour.  So when Helen starts, the distance between them is 256-18=238km.<br>
When both are traveling, they are approaching each other at a rate of 72=64=136 km/h.  The time required for them to close the distance of 238km at a rate of 136 km/h is 238/136 = 7/4 hours.<br>
So they will meet 7/4 hours after 2:15pm, which is 4pm.<br>
ANSWER: They will pass each other at 4pm<br>