Bob runs 6 miles per hour. His friend Jim runs at 9 miles per hour. If Bob has a 1 mile head-start, how many minutes will it take before Jim catches him?
Bob runs .1 miles per minute because 6 / 60 = 
<gadget id="calculator">6/60</gadget>
<output>1/10 = around 0.1</output>
.1.
Jim run at .15 miles per minute 9 / 60 = 
<gadget id="calculator">9/60</gadget>
<output>3/20 = around 0.15</output>
.15.
We know that .1(Number of Minutes) + 1 = .15(Number of Minutes)
Therefore 1 = .05(Number of minutes)
Therefore (Number of minutes) = 20 because 1 / .05 = 
<gadget id="calculator">1/.05</gadget>
<output>20</output>
20.

<result>20</result>