Find the equation of the line through (2 , -4) whose intercepts are numerically equal but of opposite sign

Which of the following can be used to explain a statement in a geometric proof?

At store a, erasers are sold individually. the cost y of x erasers is represented by the equation y=0.75x. the costs of erasers at store b are shown in the graph.

Milk and ice cream are mixed together for a recipe. the total volume of the mixture is 1 cup. if the milk contains 2% fat, the cream contains 18% fat ,and the mixture contains 6% fat ,how much cream is in the mixture