Simplifying
12x + 10 + 3 + 8x = 0
Reorder the terms:
10 + 3 + 12x + 8x = 0
Combine like terms: 10 + 3 = 13
13 + 12x + 8x = 0
Combine like terms: 12x + 8x = 20x
13 + 20x = 0
Solving
13 + 20x = 0
Solving for variable 'x'.
Move all terms containing x to the left, all other terms to the right.
Add '-13' to each side of the equation.
13 + -13 + 20x = 0 + -13
Combine like terms: 13 + -13 = 0
0 + 20x = 0 + -13
20x = 0 + -13
Combine like terms: 0 + -13 = -13
20x = -13
Divide each side by '20'.
x = -0.65
Simplifying
x = -0.65
Remember PEMDAS
Do parentheses, results in 25. So whats left is 87-25*(-3)+9
Then you multiply -25 by -3, answer is 75. 87+75+9
Add all of them up. 171
The answer is 171!
the height of the pentagonal pyramid is 5. 70 meters
<h3>Volume of a regular pentagonal pyramid</h3>
The formula for determining the volume of a regular pentagonal pyramid is given as;
V=5/12tan(54°)ha^2
Where
- a is the base edge
- h is the height
We have the volume to be;
volume = 82. 5 cubic centers
height = h
a = 5m
Substitute the values
×
×
×
×
×
× 
Make 'h' subject of formula

h = 5. 70 meters
The height of the pentagonal pyramid is 5. 70 meters
Thus, the height of the pentagonal pyramid is 5. 70 meters
Learn more about a pentagonal pyramid here:
brainly.com/question/16315924
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Answer:
answer is 12
Step-by-step explanation:
if you take 15 and subtract it by 7 that would give you the number of neon tetra fish, then you can add 4 to give you your total number which is 12 :)