Answer:
5x4+80
Step-by-step explanation:
The probability that one of each color is selected is 
<h3>Probabilities</h3>
The probability of an event is the chances of the said event
The given parameters are:
- Total = 10
- Red = x
- Blue = 10 - x
<h3>Calculating the required probability</h3>
The probability that one of each color is selected is calculated as follows:

So, we have:

This gives

Take LCM

Simplify the above expression

Expand

Hence, the probability that one of each color is selected is 
Read more about probabilities at:
brainly.com/question/7965468
Yes... indeed it is 1/8 because
125/1000 In simplest form is 1/8
So first create and define your variables:
Z = amount of zebra fish
N = amount of neon tetras
Now create your equations:
2z+2.15n=31.20
z+n=15
This is your system. There are multiple methods to use but in this problem I’ll use the substitution method by simplifying the bottom equation.
2z+2.15n=31.20
z=15-n
Now I’ll plug the bottom equation into the top one.
2(15-n)+2.15n=31.20
And just solve from here.
30-2n+2.15n=31.20
0.15n=1.20
n=8
So he bout 8 neon tetras, and 15-8= 7, so he bought 7 zebra fish