Estimating Useful Life, Percent Used Up$,$ and Gain or Loss on Disposal

Required

a$.$ Compute the average useful life of Husky Energy's depreciable assets in $2018.$ Assume that land is $10\%$ of "Refining."

Note: Round your answer to one decimal place $($for example, enter $6\mathrm{.}8$ for $6\mathrm{.}77555).$

years