Among the widowed female customers, give the income of those who has an level of education of 5 and below.
widowed female customers refer to SEX = 'Female' where MARITAL_STATUS = 'Widowed'; level of education of 5 and below refers to EDUCATIONNUM ≤ 5;
SELECT INCOME_K FROM Demog WHERE GEOID IN ( SELECT GEOID FROM Customers WHERE EDUCATIONNUM < 5 AND SEX = 'Female' AND MARITAL_STATUS = 'Widowed' )