=
IF (
    Customers[Age] <= 18,
    "18 and Under",
    IF (
        Customers[Age] > 18
            && Customers[Age] <= 30,
        ">18 and <=30",
        IF (
            Customers[Age] > 30
                && Customers[Age] <= 40,
            ">30 and <=40",
            IF (
                Customers[Age] > 40
                    && Customers[Age] <= 50,
                ">40 and <=50",
                IF ( Customers[Age] > 50 && Customers[Age] <= 60">50 and <=60"">60" )
            )
        )
    )
)
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