Cost price CP of the 100 oranges = \(\frac{100}{5}\) x N40.00
selling price SP of the 100 oranges = \(\frac{100}{20}\) x N120
= N600.00
so, profit or loss per cent
= \(\frac{SP - CP}{CP}\) x 100%
= \(\frac{600 - 800}{800}\) x 100%
= \(\frac{-200}{800}\) x 100%
Hence, loss per cent = 25%