For each city, calculate each year's precipitation and temperature anomaly values. To do this, program the equation "=X-AVERAGE($X$3:$X$76)", where "X" is the specific column reference for each of the datasets you're calculating the anomaly for (e.g.: in column E you will calculate column D values, so it will be "=D3-AVERAGE($D$3:$D$76)". The use of the "$" is called "absolute reference". It allows the chosen cells to remain constant when you autofill and are crucial for correctly calculating the long-term average, so don't leave them out.