WDI hires outside environmental consultants to frequently test the sites for

contaminants and estimate future retirement costs. Because there are many

assumptions required to estimate these costs, the outside engineers' report usually

provides a range of reasonable estimates. The most recent report was as follows:

Low end of the range: $5,000,000 on initial closure in year 20, and then $500,000

annually for 15 years.

High end of the range: $11,000,000 on initial closure in year 20, and then $350,000

for 25 years.

All costs should be discounted using a rate of 7%.

Historically, WDI has used the high end of the range to estimate the asset retirement

obligation. Marlene would like WDI to now use the low end of the range to calculate the

liability to be reported at December 31, 2020. The unaudited balance has been adjusted

for accretion only.

my question : How can i recalculate the liability using the low range using the discounting approach?? PLEASE HELP