This year Leron and Sheena sold their home for $750000 after all selling costs

This year Leron and Sheena sold their home for $750000 after all selling costs. Under the following scenarios how much taxable gain does the home sale
generate for Leron and Sheena?

a. Leron and Sheena bought the home three years ago for $150000 and lived in the home until it sold.

b. Leron and Sheena bought the home 1 year ago for $600000 and lived in the home until it sold.

c. Leron and Sheena bought the home five years ago for $500000. They lived in the home for three years until they decided to buy a smaller home. Their
home has been vacant for the past two years.