The sum of two numbers is 15. the difference of the first number and three will equal the second number

Consider the proof. given: segment ab is parallel to line de. prove: what is the missing statement in step 5?

Let f(x) = 3 − x . find the average rate of change of f(x) from x = a to x = a + h and simplify your answer so that no single factor of h is left in the denominator.

Which best describes the function on the graph? direct variation; k = −2 direct variation; k = -1/2 inverse variation; k = −2 inverse variation; k = -1/2