Speed is \(\frac{distance}{time}\), so because you already know the time(.5 + 1 + .5 + 2 = 4 hours), you want to find the distance traveled.
\(\frac{Speed}{time} = \frac{\frac{distance}{time}}{time}=\frac{distance}{\frac{time}{time}}=distance\)
So you set it up like this:
\(\frac{20mph}{.5\ hour}= 10 miles \\
\frac{40mph}{1\ hour}= 40 miles\\
\frac{30mph}{.5\ hour}= 15miles\\
\frac{50mph}{2\ hours}=100miles \\
Add\ them:\\
10+40+15+100=165miles\)
You traveled 165 miles total.
