SOLUTION: bill leaves for school walking at 4mph. his brother larry leaves 30minutes later on his bike traveling at 12mph. how long will bill have walked before his brother catches up to h

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: bill leaves for school walking at 4mph. his brother larry leaves 30minutes later on his bike traveling at 12mph. how long will bill have walked before his brother catches up to h      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 715972: bill leaves for school walking at 4mph. his brother larry leaves 30minutes later on his bike traveling at 12mph. how long will bill have walked before his brother catches up to him.
Answer by jndarrell(58) About Me  (Show Source):
You can put this solution on YOUR website!
It's difficult to draw the Rate/Time chart but you can draw your own and fill in the information we gather here:
Bill
Rate: 4mph
Time: x (what we are looking for)
Larry
Rate: 12mph
Time: x-30min
Since we were not provided a distance, we will set them equal to each other using RATE*TIME
4x=12(x-30)
DISTRIBUTE THE 12
4x=12x-360
Get x on one side of the equation...substract 12x from both sides.
-8x=-360
DIVIDE BOTH SIDES BY -8 TO GET x ALONE
x=45 (positive 45 b/c a -/-=+)
Plug our solutions back in the chart.
Bill
Rate: 4mph
Time: 45
Larry
Rate: 12mph
Time: 45-30min=15min
We were asked to find the distance for Bill. 4mph in 45min. 45min=0.75hrs
4*.75=3miles
Always remember your units in your final solution, and always go back and double check exactly what the question asked you to find, don't just stop at "x="