SOLUTION: A train traveling 100 miles at m miles per hour arrived at its destination 1 hour late.How many miles an hour should it have traveled to arrive on time ?

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Question 867370: A train traveling 100 miles at m miles per hour arrived at its destination 1 hour late.How many miles an hour should it have traveled to arrive on time ?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +t+ = the time in hours to arrive on time
+d+=+r%2At+
+100+=+m%2A%28+t+%2B+1+%29+
+100+=+m%2At+%2B+m+
+m%2At+=+100+-+m+
+t+=+%28+100+-+m+%29+%2F+m+
------------------------------
+100+=+r%2A%28+100+-+m+%29+%2F+m+
+r+=+100m+%2F+%28+100+-+m+%29+
is the rate to arrive on time
-----------------------------------
check:
Suppose +m+=+75+
+100+=+m%2A%28+t+%2B+1+%29+
+100+=+75%2A%28+t+%2B+1+%29+
+t+%2B+1+=+4%2F3+
+t+=+1%2F3+
----------------------
+r+=+100m+%2F+%28+100+-+m+%29+
+r+=+100%2A75+%2F+%28+100+-+75+%29+
+r+=+7500+%2F+25+
+r+=+300+
---------------------
+d+=+r%2At+
+100+=+300%2At+
+t+=+1%2F3+
OK