A student goes to school at a speed of 5\(\frac{1}{2}\) km/h and comes back at a speed of 5 km/h.  If he takes 5\(\frac{1}{4}\) hours for entire journey.  Find the distance.

22 km \(\frac{33}{2}\)  \(\frac{55}{2}\)  33 km

\(\frac{55}{2}\)

D = \(\frac{2 × 11/2 × 5}{11/2 + 5}\) × \(\frac{21}{4}\)    = \(\frac{11 × 5 × 2}{21}\) × \(\frac{21}{4}\) = \(\frac{55}{2}\)