 OK, this 5.7 is an interesting problem here. We are trying to compare the prices of two fuels. Natural gas, which sells for $9.74 per MCF. And we also have oil that sells at $0.99 per gallon. We're trying to compare the prices of these two and choose which one is the best fuel or cheapest fuel. So we need to calculate the price per million BTUs so that we can compare these two fuels. And we also know the furnace efficiencies of each of these. Natural gas furnace efficiency is 0.9. And we know the oil furnace efficiency is 0.8. It's given. So we need to calculate the actual cost and compare the costs. Natural gas, actual cost, will be cost per unit fuel, which is $9.74 per MCF divided by the heating value per unit fuel. Heating value for this one happens to be 1 million BTUs per MCF. And we have to multiply by the efficiency here in the denominator, which is 0.9. So the natural gas price turns out to be $10.82 or 83 cents per million BTUs. When you do similar calculation for oil here, the actual price per unit is $0.99 per gallon here. And how many million BTUs do we get per gallon? 0.13 million BTUs. We have done this before. Have to have the same units here, gallons and gallons and MCF and MCF here in this case. And times the efficiency is 0.8. So the price works out to be $9.50 per million BTUs. Same million BTUs would cost $10.80 for natural gas, and oil would be $9.50. So oil is cheaper.