After t days, the mass m, in grams, of 80 grams of a certain radioactive element is given by the function m (t) = 80(0.91). What is the daily percent decay rate of the element?
Round your answer to the nearest whole percent.
% decay each day

Two customers went to a post office. first customer paid $12 for 14 and 5 envelopes the second paid 24.80 for 10 postcards and 15 envelopes. what is cost of each envelope?

3x + 4y = 5 x- 3y = -7 solve by substitution

The edge of a cube was found to be 30 cm with a possible error in measurement of 0.4 cm. use differentials to estimate the maximum possible error, relative error, and percentage error in computing the volume of the cube and the surface area of the cube. (round your answers to four decimal places.) (a) the volume of the cube maximum possible error cm3 relative error percentage error % (b) the surface area of the cube maximum possible error cm2 relative error percentage error %