The sum of two numbers is 84. the first is 9 more than 4 times the second. find the first number.

The first number is 69.  

Step-by-step explanation:

step 1. Let x be the second number. Let 9+4x is be first number.  

Step 2. x+9+4x=84 The sum of two numbers is 84.  

Step 3. Simplify: 5x+9=84.  

Step 4. Subtract 9 to both sides of equation: 5x+9-9=84-9=75  

Step 5. Simplify and divide by 5: 5x=75 or x=15. Then 9+4x=9+4(15)=69  

Step 6. The first number is 69.  

I hope the above steps were helpful.

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.