Because everything has to equal 360 so, 360 -109 two times because obvious that it’s the same on both side so -109+-109 is -218 so 360-218 it gives you -142 so divid that for two and you get x=71
If it took 4 miles per hour you multiply that twice cuss its traveling back then forth so you repeat the same process 30 miles times 2 which is 60 hope this helps.
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