A 2540 g sample of an oxide of tin was heated in the air

Question

Compute all parts of given question:

Question: A 2.540 g sample of an oxide of tin was heated in the air until the mass of the sample no longer changed, and 2.842 g of tin (IV) oxide (SnO2) was obtained as a result of the heating.

Part A: What is the mass percent of tin in SnO2?

Part B: What is the mass of tin in the final sample?

Part C: What was the mass of tin in the original sample?

Part D: What was the mass of oxygen in the original sample?

Part E: What was the number of moles of tin in the original sample?

Part F: What was the number of moles of oxygen in the original sample?

Part G: What is the formula (SnxOy) of the original oxide of tin?

I need help to determine the number of moles of oxygen in the original sample.