Hello experts, can somebody help me answering the next questions please, thank you

8. Epinephrine (C9H33NO3) is a neurotransmitter, a substance that sends signals from one nerve to another. What is the percent composition by mass of each element in the compound? 9. Phytosterol (C29H50O) is a compound that is needed in your body to form steroid hormones, bile acid, and vitamin D. Calculate the percent composition of C,H and O to three significant figures: 10. A certain newly synthesized compound is known to contain the elements zinc and axygen. When a 20.00g sample of the compound is decomposed, 16.07g of zinc remains. Determine the percent composition of the compound