Answer :
Clark got to school at 8:19 am.
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36 minutes can be split up into 6 minutes and 30 minutes.
Six minutes after 7:43 am is 7:49 am.
Thirty minutes after 7:49 am is 8:19 am.
if he left at 7:43 am he was 17 minutes from 8:00 (subtracting 43 from 60)
36 min less 17= 19
therefore arrived at 8:19 am