SOLUTION: Judy walked into the country at 5 km per hour and then rode a bus back home at 30 kilometers per hour. It was a long trip as she was gone 21 hours. How far did she walk?

Algebra ->  Equations -> SOLUTION: Judy walked into the country at 5 km per hour and then rode a bus back home at 30 kilometers per hour. It was a long trip as she was gone 21 hours. How far did she walk?       Log On


   

Question 1101746: Judy walked into the country at 5 km per hour and then rode a bus back home at 30 kilometers per hour. It was a long trip as she was gone 21 hours. How far did she walk?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +d++ = the one-way distance she traveled in km
Let +t+ - her time in hrs spent walking
+21+-+t+ = her time in hrs spent riding on the bus
(1) +d+=+5t+
(2) +d+=+30%2A%28+21+-+t+%29+
-----------------------------
+5t+=+30%2A%28+21+-+t+%29+
+5t+=+630+-+30t+
+35t+=+630+
+t+=+18+
and
+21+-+t+=+21+-+18+
+21+-+t+=+3+
----------------------
She walked for 18 hrs and
rode the bus for 3 hrs
---------------------------
check:
(1) +d+=+5t+
(1) +d+=+5%2A18+
(1) +d+=+90+ km
and
(2) +d+=+30%2A%28+21+-+t+%29+
(2) +d+=+630+-+30t+
(2) +d+=+630+-+30%2A18+
(2) +d+=+630+-+540+
(2) +d+=+90+ km
OK