SOLUTION: Pa got in his '29 Ford and started driving west from Jackson at a constant speed of 30 miles per hour. An hour later Ma got in her '31 Buick and started driving west from Jackson a

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: Pa got in his '29 Ford and started driving west from Jackson at a constant speed of 30 miles per hour. An hour later Ma got in her '31 Buick and started driving west from Jackson a      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


   



Question 939447: Pa got in his '29 Ford and started driving west from Jackson at a constant speed of 30 miles per hour. An hour later Ma got in her '31 Buick and started driving west from Jackson at a constant speed. After driving 4 hours Ma had passed Pa and was 10 miles ahead of him. How fast was Ma going?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Pa's head start was +30%2A1+=+30+ mi
Start a stop watch when Ma leaves
Let +d+ = the distance Ma travels
in +4+ hrs
Let +r+ = Ma's rate in mi/hr
--------------------
Pa's equation:
(1) +d+-+30+-+10+=+30%2A4+
Ma's equation:
(2) +d+=+r%2A4+
----------------
(1) +d+-+40+=+120+
(1) +d+=+160+
and
(2) +160+=+r%2A4+
(2) +r+=+160%2F4+
(2) +r+=+40+
Ma's rate is 40 mi/hr
--------------------
check:
From the time Pa leaves he covers
+30%2A%28+1+%2B+4+%29+=+150+ mi
This is +10+ mi less than Ma's
distance as it should be