Steven cuts a 25 foot board piece into 2 pieces

Which expression is equivalent to (3^2)^-2 a.-81 b.-12 c.1/81 d.1/12

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

Angles r and s are complementary. the measure of angle r is 31 degrees. which equation can be used to find angle s?