Question

you are driving 50 miles per hour. If you decrease the time it takes you travel 1 mile by 8 seconds. What is your new speed?

Answer 1

keeping in mind that an hour has 60 minutes, and each minute has 60 seconds, so then 1 hour has 60*60 seconds, namely 3600 seconds

`\cfrac{\stackrel{miles}{50}}{\underset{seconds}{3600}}\implies \cfrac{\stackrel{mile}{1}}{\underset{seconds}{72}}\hspace{5em}\cfrac{\stackrel{mile}{1}}{\underset{\textit{decreased by 8 seconds}}{72-8}}\implies \cfrac{\stackrel{mile}{1}}{\underset{seconds}{64}}`

now, let's convert that to miles per hours

`\cfrac{1m}{64s}\cdot \cfrac{3600s}{1hr}\implies \cfrac{3600m}{64hr}\implies \cfrac{\stackrel{miles}{225}}{\underset{hours}{4}}\implies 56.25~(miles)/(hour)`