SOLUTION: Mary drove to work at 40mph and got to work 1 minute late next day she went at 45 mph and got There 1 minute early how far does she live

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Question 809804: Mary drove to work at 40mph and got to work 1 minute late next day she went at 45 mph and got There 1 minute early how far does she live
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +d+ = the distance she must drive
Let +t+ = driving time in hrs that gets her there on time
-------------
+d+=+40%2A%28+t+%2B+1%2F60+%29+
+d+=+45%2A%28+t+-+1%2F60+%29+
------------------
By substitution:
+40%2A%28+t%2B1%2F60+%29+=+45%2A%28+t-1%2F60+%29+
+40t+%2B+40%2F60+=+45t+-+45%2F60+
+5t+=+85%2F60+
+5t+=+17%2F12+
+t+=+17%2F60+
---------------
+d+=+40%2A%28+t+%2B+1%2F60+%29+
+d+=+40%2A%28+17%2F60+%2B+1%2F60+%29+
+d+=+40%2A%28+18%2F60+%29+
+d+=+40%2A%283%2F10%29+
+d+=+12+
She lives 12 mi away
check:
+d+=+45%2A%28+t+-+1%2F60+%29+
+12+=+45%2A%28+t+-+1%2F60+%29+
+12+=+45t+-+45%2F60+
Divide both sides by +3+
+4+=+15t+-+15%2F60+
+4+=+15t+-+1%2F4+
+16+=+60t+-+1+
+60t+=+17+
+t+=+17%2F60+
OK