If a scientist has 4x 10^7 cells in a growing culture, and introduces 4 x 10^9 more to the culture, then how many cells does the scientist have altogether? Your answer should be in scientific notation.
a. 404 x 10^7
b. 8 x 10^16
c. 4.04 x 10^9
d. 1.6 x 10^17

Which statement explains how you could use coordinate geometry to prove the opposite sides of a quadrilateral are congruent? a. use the slope formula to prove the slopes of the opposite sides are the same. b. use the slope formula to prove the slopes of the opposite sides are opposite reciprocals. c. use the distance formula to prove the lengths of the opposite sides are the same. d. use the distance formula to prove the midpoints of the opposite sides are the same.