a is the intercept value i.e., the point when the independent value is equal to zero. Here it is not relevant as when every independent variable is equal to 0, profit cannot be -7.24. b1, b2, b3, b4 is the coefficient of the independent variables. For example, here the value of b1 = 0.02 for X1 i.e., SALES. It is the value with which the dependent variable will increase with unit increase in SALES keeping other independent variables unchanged