Aseries contains 18 numbers and has a sum of 4,185. the last number of the series is 275. what is the first number?

If the series is made up of numbers in an arithmetic progression, you have



where is the first term and is the common difference between terms.

Since the last term in the series is , you have



Solve the system



and you'll find that the first term is (with ).

You need to show the box plots