CSEC Mathematics · January 2015 · Paper 2 · Question 3(a)(ii)

In a survey of 30 families, the findings were that: 15 families owned dogs, 12 families owned cats, x families owned BOTH dogs and cats, 8 families owned NEITHER dogs NOR cats. Given that U = {families in the survey}, C = {families who owned cats}, D = {families who owned dogs}.

Write an expression, in x, which represents the TOTAL number of families in the survey.