Find the numbers whose sum is 15 if twice the first number minus the second number equals

Which approach to the theory-and-research cycle does the following sequence reflect: (1) specific observations suggest generalizations, (2) generalizations produce a tentative theory, (3) the theory is tested through the formation of hypotheses, and (4) hypotheses may provide suggestions for additional observations?

#1-20 state whether the angles are alternate interior, alternate exterior, vertical, or corresponding angles.

Negative 5 1/12 + negative 4 1/4 + 6 3/4