Given
216 sections : 15%
want to know
X sections : 100%
Write the proportion equation
216/15 = X/100
Cross multiply
216*100=15*X
Solve for X
X=21600/15=1440
so there used to be 1440 sections.
This is the answer, and the working
Answer:
(-2, 6)
General Formulas and Concepts:
<u>Pre-Algebra</u>
- Order of Operations: BPEMDAS
- Equality Properties
<u>Algebra I</u>
- Solving systems of equations using substitution/elimination
- Solving systems of equations by graphing
Step-by-step explanation:
<u>Step 1: Define systems</u>
4x - 2y = -20
7x + 2y = -2
<u>Step 2: Rewrite systems</u>
4x - 2y = -20
- Add 2y to both sides: 4x = 2y - 20
- Divide 4 on both sides: x = 1/2y - 5
<u>Step 3: Redefine systems</u>
x = 1/2y - 5
7x + 2y = -2
<u>Step 4: Solve for </u><em><u>y</u></em>
<em>Substitution</em>
- Substitute in <em>x</em>: 7(1/2y - 5) + 2y = =-2
- Distribute 7: 7/2y - 35 + 2y = -2
- Combine like terms: 11/2y - 35 = -2
- Add 35 to both sides: 11/2y = 33
- Isolate <em>y</em>: y = 6
<u>Step 5: Solve for </u><em><u>x</u></em>
- Define original equation: 7x + 2y = -2
- Substitute in <em>y</em>: 7x + 2(6) = -2
- Multiply: 7x + 12 = -2
- Subtract 12 on both sides: 7x = -14
- Divide 7 on both sides: x = -2
<u>Step 6: Graph systems</u>
<em>Check the system.</em>
Well, the square root of 12 is 3.464101615
I don't know if that is factor-able. It looks like you could just subtract and get 64t. which would lead to the answer being zero since you divide by zero when isolating the variable t.