Nadine sells user-friendly software. her firm's production function is f(x1, x2) = x1 + 2x2, where x1 is the amount of unskilled labor and x2 is the amount of skilled labor that she employs.

Match the following reasons with the statements given to create the proof. 1. do = ob, ao = oc sas 2. doc = aob given 3. triangle cod congruent to triangle aob vertical angles are equal. 4. 1 = 2, ab = dc if two sides = and ||, then a parallelogram. 5. ab||dc if alternate interior angles =, then lines parallel. 6. abcd is a parallelogram cpcte