Final answer:
Married working-class women in late nineteenth-century western Europe commonly supplemented the family's income through cottage industry work, such as piecework done at home.
Step-by-step explanation:
Married working-class women in western Europe commonly supplemented the family's income in the late nineteenth century by engaging in cottage industry work. Their work involved activities that could be done from home, allowing them to also care for their families. Women did piecework, assembling small items at home and getting compensated based on the number of items produced, such as toys, costume jewelry, or clothing. This adaptation of household skills for income generation was significant then, as it also fulfilled social expectations of women's roles within the home.