I don’t understand the equation

The local farm is advertising a special on fresh picked peaches. the farm charges $4.25 to pick your own peck of peaches and $3.50 for each additional peck you pick. write an equation for the total cost of peaches in terms of the number of pecks. deine your variables. how much does it cost to pick 3 pecks of peaches?

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Solve the equation for b: a= (1/2)(b)(h)