 For this problem, we are trying to calculate the heat loss. We are given the dimensions. We are given the r value and the temperature difference. Those are the quantities that we need to calculate the heat loss, basically. The dimensions are the wall dimensions are 8 feet, and this side is 10 feet. So the area is 8 times 10 will be 80 square feet, and we are also given that inside temperature is 70 degrees Fahrenheit, and outside temperature, average outside temperature is 43 degrees Fahrenheit. Therefore, the difference or delta T is equal to 27 degrees Fahrenheit. Now, area is given. A is, we already calculated, 80 square feet, and r value is also given as 22, which is 22 foot square degrees Fahrenheit hour over BTU. Now, heat loss, BTUs per hour is equal to area times delta T divided by r value. And in this case, it is 80 foot square times 27 degrees Fahrenheit divided by 22 r value foot square degrees Fahrenheit hour over BTU. So this will be equal to, here you can cancel foot square, foot square, degrees Fahrenheit, degrees Fahrenheit, we are left with BTUs per hour. And the heat loss comes out to be 98.2 BTUs per hour.