A 4.2 m self-propelled combine harvester operating at a forward speed of 3.5 km.h⁻¹ is used to harvest wheat in an area of 300 ha in a year at a field efficiency of 75%. Consider the variable cost to be linearly related to the actual hours of operation. To bring down the cost of operation per hour by 15%, the change in area required to be harvested per year, in ha, is _______. (Rounded off to 2 decimal places)