Tan a= 12/15, a lies in quadrant 3, and cos x= -20/29, x lies in quadrant 2. find sin (a+x). a) 345/377 b) 135/377 c) -152/377 d) 352/377

Parabolas y=−2x^2 and y=2x^2 +k intersect at points a and b that are in the third and the fourth quadrants respectively. find k if length of the segment ab is 5.

Ascientist has discovered an organism that produces five offspring exactly one hour after its own birth, and then goes on to live for one week without producing any additional offspring. each replicated organism also replicates at the same rate. at hour one, there is one organism. at hour two, there are five more organisms. how many total organisms are there at hour seven? 2,801 19,531 19,607 97.655

Having a hard time understanding this question (see attachment).