FAMILY X'S EXPENDITURES AS A PERCENT OF ITS GROSS ANNUAL INCOME * Family X's gross income is the sum of Mr. X's income and Mrs. X's income. In 1983 Mr. and Mrs. X each had an income of $25,000. If Mr. X's income increased by 10 percent from 1983 to 1984, by what percent did Mrs. X's income decrease for the same period?