10 Sara was thinking of a number. Sara adds 19 to it, then doubles it and gets an answer of 39.2. What was the original number?

What is the binomial expansion of (2x-3)^5

Find the measure of the interior angles of the following regular polygons: a triangle, a quadrilateral, a pentagon, an octagon, a decagon, a 30-gon, a 50-gon, and a 100-gon.

Adrawer contains 12 identical white socks, 18 identical black socks and 14 identical brown socks. what is the least number of socks you must choose, without looking, to be certain that you have chosen two socks of the same colour?