What's the 25th term if the first term is 3 and the common difference is -21

This race was first held in 1953 on august 16th. every decade the race finishes with a festival. how many years is this?

An automated water dispenser fills packets with one liter of water on average, with a standard deviation of 5 milliliter. the manual says that after a year of operation the dispenser should be tested to see if it needs recalibration. a year later a number of filled packets are set aside and measured separately. it is found that the average packet now contains about 0.995 liters. does the dispenser need calibration? explain your answer.

Savannah talked for 6 minutes on the phone. catherine talked for n minutes. catherine talked 3 times as long as savannah. how long did nathan talk?