if a store uses a markup of 87.5% what should the equation be that gives the retail price y with an original cost of x

When y’all answer can y’all explain too !

Which of the following correctly justifies statement four of the two column proof? a. corresponding angles theorem b. transitive property of equality c. vertical angle theorem d. substitution property of equality

6x + 3y = -6 2x + y = -2 a. x = 0, y = -2 b. infinite solutions c. x = -1, y = 0 d. no solution