Describe the pattern, write the three next terms and find the expression for the nth term: 6, 9, 12, 15...

x+y=90

x=30-y=x

step-by-step explanation:

if you understand you will get the 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.  

i think it will be zero as slope has a formula of difference between initial and final distance divided by itz time interval