19. Amy has 8 coins worth $1.40. Some of the coins are nickels and some are quarters. How many of each coin does Amy have?

5 quarters and 3 nickels

Step-by-step explanation:

x = nickels

y = quarters

x + y = 8

x(0.05) + y(0.25) = 1.40

3 + 5 = 8

3(0.05) + 5(0.25) = 1.40

0.15 + 1.25 = 1.40

1.25 + 0.15 = 1.40

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.  

14.3

step-by-step explanation:

add all the numbers together.

9 + 12 + 15 + 16 + 17 + 17 = 86

now, divide 86 by how many numbers we have: 6.

86 / 6 = 14.3