When we look at the coefficients, there is a common factor of 4 with 16 and 4. The p's are also common factors, and we can take out a common factor of x^3. We can combine these common factors and take them out of the equation at the same time.
The difference in elevation equals subtraction. In other words 39ft subtracted by 8ft equals 31ft. So New Orleans, Louisiana is 31ft ABOVE sea level compared to EL Centro, California.
