price A= ßo + ß1nox + ß₂rooms + ß3dist + ß4 (rooms x dist) + u

Variable price refers to the price of a house, regressor rooms refers to the number of rooms in the house and dist to distance of the house from the city centre. What is the expected effect of variable dist for houses with 7 bedrooms? How would you find out whether the variable dist is statistically significant?