Mrs Tan bought 24 identical packets of nuts for $30. After the price of each packet of nuts had increased, she could only buy 20 packets with the same amount of money. What was the percentage increase in the price of each packet of nuts?

1. Calculate the original price of one packet of nuts

Original price = $\frac{30}{24} = \char36{}1.25$

2. Calculate the new price of one packet of nuts

New price = $\frac{30}{20} = \char36{}1.50$

3. Calculate the percentage increase in price

Increase in price = $1.50 - 1.25 = \char36{}0.25$
Percentage increase = $\frac{0.25}{1.25} \times 100\% = 20\%$