High-low method

see i am ACCA student i think i can help you hope you do understand

u see high low method simply means the use of :
1) a.High cost & b. low cost
2) a.high unit & b. low unit
think of it
next thing you must remember is that
the high cost must be corresponding to the high unit or vice versa until specified by the question similar is the case for units too

the common purpose of high low method is used to derive the variable and Fixed element of the cost to do so u must use the formula

variable cost per unit = high cost – low cost / high unit -low unit
, whose result will of course give you the variable cost per unit
next thing to keep in mind before calculating the fixed element is to think of the semi-variable cost
remember that semi-variable cost (Total cost) = Fixed cost + Total variable cost (variable cost p.u * units of production)

now you will have all those elements that you will need to calculate the fixed cost
as the fixed cost element remains the same now you can calculate total cost for the required units as question desire
hope u did understand it