Ranger Pressure Cleaners has total monthly costs of $5,800 when 3,200 units are produced and $6,425 when 3,700 units are produced. If the high-low method is used, how much is the estimated total monthly fixed cost?

I took 6425-5800 and then 3700-3200 which gives me 625/500= 1.25. I do not know how to get the fixed cost from here, i thought it was the high amount X the fixed costs