Consider the relationship between ŷ = annual income (in thousands of dollars) and x₁ = number of years of education by x₂ = gender. Many studies in the United States have found that the slope for a regression equation relating y to x₁ is larger for men than for women. Suppose that in the population, the regression equations are μ_y = -10 + 4x₁ for men and μ_y = -5 + 2x₁ for women. Explain why these equations imply that there is interaction between education and gender in their effects on income.