Linda starts a chain letter and sends it to three friends. Each of the three friends sends the letter to 3 other friends and the sequence is repeated. Assuming that no one breaks the chain,
how many letters will have been sent from the first through the sixth mailings?

PLEASE HELP WITH FORMULA HUHU

On the first of each month, shelly runs a 5k race. she keeps track of her times to track her progress. her time in minutes is recorded in the table: jan 40.55 july 35.38 feb 41.51 aug 37.48 mar 42.01 sept 40.87 apr 38.76 oct 48.32 may 36.32 nov 41.59 june 34.28 dec 42.71 determine the difference between the mean of the data, including the outlier and excluding the outlier. round to the hundredths place. 39.98 39.22 0.76 1.21

Find the perimeter of the triangle with vertices  d(3, 4),  e(8, 7), and  f(5, 9). do not round before calculating the perimeter. after calculating the perimeter, round your answer to the nearest tenth.  

Aye asap pls ! markin da brainiest too ! btw da step choices are all add, distribute, divide, n subtract