Can someone help me please

If p(a) = 0.70 and p(b) = 0.20, then a and b are independent events if

Reinel saves 30% of every pay check. his paycheck last week was 560$. how much did reniel save last week?

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