i need a step by step explanation please

Maintenance conts at Seaside Manufacturing over the past sk months are lived in the folosing table. Using the high - low metrod, what would the total maintenance costs be if 17,700 machine hours wore used? (Round intermedisry caloulations to the nearist cent. Use the "high" data month if calculate your final answer. Do not use the "low" month, as z will result in an approxinsition of the cost.) A. $14,820 12. $28,620 c. $+,380 D. $10,620