how do you determine the fraction of parent isotope remaining after 20,000 years if the isotope used has a half life of 5000 years

Line l passes through points (0,4) and (3,6) what is the slope of a line that is parallel to line l -2/3 -3/2 2/3 3/2

Solve 3x-18=2y and 5x-6y=14 by elimination or substitution . show all !

Adecorative window is made up of a rectangle with semicircles at either end. the ratio of ad to ab is 3: 2 and ab is 30 inches. what is the ratio of the area of the rectangle to the combined area of the semicircles? possible answers: a. 2: 3 b. 3: 2 c. 6: π d. 9: π e. 30: π