Use two separate Calculation Steps with the Conditional Step property selected: use the ISTRUE (is Customer) and NOT (ISTRUE) (is Customer) functions in the Condition syntax.

Use two separate Calculation Steps with the Conditional Step property selected: reference just the is Customer variable in the Conditional syntax (no comparison necessary)

Use two separate Calculation Steps with the Conditional Step property selected: compare theisCustomer variable directly to the literal true and false values in the Condition syntax.

Use a single Calculation Steps with IF statement directly in the formula definition to reference the isCustomer variable and conditionally perform the appropriate calculation.