I want to know how to get the answer, not the answer itself.

Question 23 O pts A Co reported the below cost and revenue formulas. Sales $270 Cost of goods sold $120 Salaries expense $5,500 per month Utilities expense $125 plus $2.500 Rent expense $2,000 per month Misc expense $500 plus $3.25Q They planned to sell 1,800 units and they actually sold 2,100 units. Following are the actual results from the period. Sales $58,500 Cost of goods sold $24.800 $33,700 $6,000 Gross margin Salaries expense Utilities expense Rent expense Misc expense $5,480 $2,000 $2,400 Net income $10,820 What is revenue/spending variance for sales? $1,800 U O $8,100 F O $1,800 F 0 $8,100 U