SOLUTION: hello can some one solve this word problem for me? thank you It took betty 4.5 hrs to drive to her mother's house on Sat morning. On her return trip on Sun night, traffic w

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Question 883786: hello can some one solve this word problem for me? thank you


It took betty 4.5 hrs to drive to her mother's house on Sat morning. On her return trip on Sun night, traffic was heavier, so her trip took her 5 hrs. Her average speed on Sun was 7 mph slower than Sat. What was her average speed on Sun.

Found 2 solutions by lwsshak3, josmiceli:
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
It took betty 4.5 hrs to drive to her mother's house on Sat morning. On her return trip on Sun night, traffic was heavier, so her trip took her 5 hrs. Her average speed on Sun was 7 mph slower than Sat. What was her average speed on Sun.
***
let x=speed on Saturday
x-7=Speed on Sunday
distance=travel time*speed (equal for both trips)
4.5x=5(x-7)
4.5x=5x-35
0.5x=35
x=70
x-7=63
average speed on Sun=63 mph

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +d+ = the one-way distance
in miles to her mother's house
Let +s+ = her average speed in mi/hr on Sat.
+s+-+7+ = her average speed in mi/hr on Sun.
---------------------------------
Equation for Sat:
(1) +d+=+s%2A4.5+
Equation for Sun:
(2) +d+=+%28+s+-+7+%29%2A5+
--------------------
By substitution:
+4.5s+=+%28+s+-+7+%29%2A5+
+4.5s+=+5s+-+35+
+.5s+=+35+
+s+=+35%2F.5+
+s+=+70++
+s+-+7+=+63+
--------------
Her average speed on Sun was 63 mi/hr
------------
check:
(1) +d+=+s%2A4.5+
(1) +d+=+70%2A4.5+
(1) +d+=+315+ mi
and
(2) +d+=+%28+s+-+7+%29%2A5+
(2) +d+=+63%2A5+
(2) +d+=+315+ mi
OK