Atank can be filled using pipes a, b or both. it takes pipe a, running alone 18 hours to feel the tank. it takes both pipes running together 9.9 hours to fill the tank. how long does it take pipe b, running alone, to fill the tank?

What is the number 321,000,000 in scientific notation? also what is the number? ?

What is 140% of 25? because i need

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