A student has some $1 and $5 bills in his wallet. He has a total of 19 bills and that are worth $55. how many of each type of bill does he have

y= 9 ( 5 dollars bill)

x=10 ( one dollar bill)

Step-by-step explanation:

let x be the one dollar bill and y the 5 dollar bill

x+y=19 ⇒ x=19-y

x+5y=55 ( solve by substitute x=19-y)

19-y+5y=55

4y=55-19

4y=36 ⇒ y=36/4

y= 9 ( 5 dollars bill)

x+y=19

x+9=19

x=19-9

x=10 ( one dollar bill)

check :

x+5y=55

10+5(9)=

10+45 = 55 dollars

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.