A hot brick is removed from a kiln at 225°C above room temperature. Over time, the brick cools off. After 2 hours have elapsed, the brick is 30° C above room temperature. Let t be the time in hours since the brick was removed from the kiln. Let y = H(t) be the difference between the brick's and the room's temperature at time t. Assume that H(t) is an exponential function. How much time elapses before the brick's temperature is 10°C above room temperature? Round your answer to 2 places after the decimal.