Answer:
The total change in water level over the past 2 years is
.
General Formulas and Concepts:
<u>Pre-Algebra</u>
Order of Operations: BPEMDAS
- Brackets
- Parenthesis
- Exponents
- Multiplication
- Division
- Addition
- Subtraction
Fractions
Numbers
- Least Common Multiple (LCM)
Step-by-step explanation:
<u>Step 1: Define</u>
<em>Identify</em>
Year 1 water change: 
Year 2 water change: 
<u>Step 2: Find Total Water Change</u>
- [Set up] Add yearly water changes:

- [Fractions] Convert to improper:

- [Fraction] Rewrite [LCM]:

- [Order of Operations] Subtract:

- [Fraction] Convert to proper:

Let x represent the number of pounds of $10.75/lb coffee used in the mix.
.. 10.75x +3.25(100 -x) = 5.65*100 . . . . . . total cost of coffee blend
.. x(10.75 -3.25) = 100*(5.65 -3.25) . . . . . .separate x-terms from non-x terms
.. x = 240/7.5 = 32
32 pounds of $10.75/lb coffee should be used
68 pounds of $3.25/lb coffee should be used
If it is a system of two unknowns:
1) 4x-8y=5 multiple by 3
2)6x-12y=10 multiple by -2
then
12x-24y=15
-12x+24y=-20
x and y equals 0, so
Answer: no solution
You divide 13 into 250 parts which gives you 0.052, multiplied by 100 will give you the percent: 5.2%
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