If Patricia were to paint her living room alone, it would take 8 hours. Her sister Denise could do the job in 9 hours. How long would it take them working together? If needed, submit your answer as a fraction reduced to lowest terms.

The weight of a radioactive isotope was 96 grams at the start of an experiment. after one hour, the weight of the isotope was half of its initial weight. after two hours, the weight of the isotope was half of its weight the previous hour. if this pattern continues, which of the following graphs represents the weight of the radioactive isotope over time? a. graph w b. graph x c. graph y d. graph z