What is the answer 3xy+13xy-12xy=

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?

Acircle has a circumference of 7.850 units. what is its radius?

What is the solution to the division problem below x3+x2-11x+4/x+4