The original cost of hiring a caravan in Wales is £520, and the new cost in July is £800. To find the percentage increase in cost, we can use the following formula:
percentage increase = (new value - old value) / old value x 100%
Substituting the values given:
percentage increase = (800 - 520) / 520 x 100%
percentage increase = 280 / 520 x 100%
percentage increase = 53.85%
Therefore, the percentage increase in cost is 53.85%, which we can round to 2 significant figures as 54%.