4.6.PS-16 Nancy and Bill collect coins. Nancy has x coins. Bill has 2 coins fewer than three
times the number of coins Nancy has. Write and simplify an expression for the total
number of coins Nancy and Bill have.
Nancy and Bill have coins.
(Simplify your answer.)

the answer is; biodiversity resulting from few ancestors

adaptive radiation occurs when a population is subjected to a large natural environment with spatial ecological variations. the parts of the population in the different ecologies begin to adapt to their local environments. due to non-random mating across the large populations, this causes the different populations from the large population to speciate within their local environments. they, therefore, diverge to different species sharing a common ancestor.  

1) 2/5

2) zero=0/1

3) zero=0/2

4) -4/5

5) undefined=3/0

cross multiplying, we get :

⇒ (3) × (5) = (9) × (x)

⇒ 15 = 9x