Researchers are monitoring two different radioactive substances. they have 300 grams of substance a which decays at a rate of 0.15%. they have 500 grams of substance b which decays at a rate of 0.37%. they are trying to determine how many years it will be before the substances have an equal mass.

if m represents the mass of the substance and t represents the elapsed time in years, then which of the following systems of equations can be used to determine how long it will be before the substances have an equal mass?
a.

b.

c.

d.

What is the area of triangle abc if a = 8, b = 11, and c = 15?

25 ! the line of best fit is h = 5a + 86. predict the height at age 16.

Since opening night, attendance at play a has increased steadily, while attendance at play b first rose and then fell. equations modeling the daily attendance y at each play are shown below, where x is the number of days since opening night. on what day(s) was the attendance the same at both plays? what was the attendance? play a: y = 8x + 191 play b: y = -x^2 + 26x + 126 a. the attendance was never the same at both plays. b. the attendance was the same on day 5. the attendance was 231 at both plays on that day. c. the attendance was the same on day 13. the attendance was 295 at both plays on that day. d. the attendance was the same on days 5 and 13. the attendance at both plays on those days was 231 and 295 respectively.