Answer:
$2 for soda and $1.5 for a bottle of water
Step-by-step explanation:
You start by turning both situations into an equation
Let x represent bottles of water and y represent sodas
Saturday:

Sunday:

You then want to start by cancelling out the x in this equation, to do that you want 40x to become -50x so you:
50÷40=1.25
You then times the whole equation by -1.25
40x+25y=110
×-1.25
-50x+-31.25y= -137.5
You then add this equation by Sunday's equation
50x+45y=165
-50x+-31.25y=-137.5
13.75y=27.5
You now want to make the co-efficient of y a whole number (for example 15) so you divide 15/13.75=1.09 recurring
13.75y=27.5
×1.09 recurring
15y=30
15y/15=30/15
y=2
Now that we know y = 2
We can use either Saturday or Sunday's equation to figure out the value of 
Let's use Sunday's:
50x+45×2=165
50x+90=165
50x+90-90=165-90
50x/50=75/50
x=1.5
Let's check our answer with Saturday's equation
40×1.5+25×2=110
This equation is correct
Therefore the prices for each beverage option is $1.5 for a bottle of water and $2 for a soda
The square root of a whole number will be rational if the whole number is a perfect square (i.e 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144 etc) and irrational otherwise.
Rational number is a number that can be described as m/n
so a fraction can be a rational number, 0.8=4/5
Irrational numbers can't be written as a fraction
The part about the number having to be a perfect square is still correct, if it's not a prefect square than it will just keep going(a decimal that never ends)
for example the square root of 0.64 is 0.8
and the square root of 10 is 3.162277...
as you can see the 0.64 one ends and is rational, whereas the 10 one just keeps going and is irrational.
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