algebra
posted by Anonymous .
Her average rate traveling uphill was 1.8 kilometers per hour and her average rate down hill was 4.2 kilometers per hour. If she spent a total of 16 hours hiking, how long was the trail?

add up the times to hike d km:
d/1.8 + d/4.2 = 16
0.5555d + .2381d = 16
d = 16/.7936 = 20.16 km