A laptop has a listed price of $549.98 before tax. If the sales tax rate 9.5%, find the total cost of the laptop with sales tax included. Round your answer to the nearest cent, as necessary

Can someone explain the elimination method to me for this problem?

Which sum or difference identity would you use to verify that cos (180° - ∅) = -cos ∅? a. sin (α -β) = sin α cos β – cos α sin β b. cos (α -β) = cos α cos β – sin α sin β c. cos (α -β) = cos α cos β + sin α sin β d. sin (α + β) = sin α cos β + cos α sin β

Which is a reasonable estimate of the amount of water in a small, inflatable pool used by children?