First you need to make your dimensions in uniform/consistent units, i.e. in feet. 1 ft = 12 inches, therefore 9 inches =ft = ft = 0.75 ft. Thus you need to multiply 17.75 ft by 11.75 ft to get the area. Use your calculator: 17.75 * 11.75 = 208.56 square feet, or 209 sq. ft. rounded Next multiply the area by $2.89 to get the cost. You will get $604. It is your answer.