What’s the area of this shape

The lines shown below are parallel. if the green line has a slope of -1, what is the slope of the red line

Adam plans to choose a video game from the section of the store where everything is 75% off. he writes the expression d-0.75d to find the sale price of the game if the original price is d dollars. gena correctly writes another expression, 0.25d, that will also find the sale price of the game if the original price is d dollars. use the drop down menus to explain each part of adams and rena's expression

Solve for x and y: 217x + 131y = 913; 131x + 217y = 827