Find the selling price- cost to store: $140 Markup: 25%

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

Answer for 10 points show work you guys in advanced < 3

Varies inversely with x. if y=8.5 when x=-1 find x when y=-1