The uphill part of the ride would have taken 16 minutes and 40 seconds.
This can be found first by determining how many miles Lauren went during the downhill portion. This can be found by multiplying the speed by the time.
5mph * .5hrs = 2 1/2 miles.
Now we can determine how far she needs to go during the uphill portion by subtracting the downhill portion from the entire ride.
3 1/3 miles - 2 1/2 miles = 5/6 miles.
Now that we know she needs to go 5/6 miles for the uphill portion, we can divide the distance by the speed.
5/6 miles / 3 mile per hour = 5/18 hours = 16.67 mins or 16 mins and 40 seconds.