Answer:
<h2>The lengths of the bases of the trapezoid:</h2><h2>
42/h cm and 84/h cm.</h2>
Step-by-step explanation:
The formula of an area of a triangle:

<em>b</em><em> </em>- base
<em>h</em> - height
We have <em>b = 21cm, h = 6cm</em>.
Substitute:

The formula of an area of a trapezoid:

<em>b₁, b₂</em> - bases
<em>h</em><em> - </em>height
We have <em>b₁ = 2b₂</em>, therefore <em>b₁ + b₂ = 2b₂ + b₂ = 3b₂</em>.
The area of a triangle and the area of a trapezoid are the same.
Therefore
<em>multiply both sides by 2</em>
<em>divide both sides by 3</em>
<em>divide both sides by h</em>


Answer:

Step-by-step explanation:
6 symbols and 4-symbol code so number of combinations wich doesn't contain the same symbol twice would be:
6•5•4•3 = 360
If code starts with a star followed by triangle that means only one posibility for first two symbols and code doesn't containing the same symbol twice means that left 4 symbols for next two.
So number of combinations of code starting with a star followed by triangle and doesn't containing the same symbol twice will be:
1•1•4•3 = 12
The probability that a randomly chosen code starts with a star followed by triangle and doesn't contain the same symbol twice:

Answer: -5.6
Step-by-step explanation:
Simplifying
(4x + -28) = 9x
Reorder the terms:
(-28 + 4x) = 9x
Remove parenthesis around (-28 + 4x)
-28 + 4x = 9x
Solving
-28 + 4x = 9x
Solving for variable 'x'.
Move all terms containing x to the left, all other terms to the right.
Add '-9x' to each side of the equation.
-28 + 4x + -9x = 9x + -9x
Combine like terms: 4x + -9x = -5x
-28 + -5x = 9x + -9x
Combine like terms: 9x + -9x = 0
-28 + -5x = 0
Add '28' to each side of the equation.
-28 + 28 + -5x = 0 + 28
Combine like terms: -28 + 28 = 0
0 + -5x = 0 + 28
-5x = 0 + 28
Combine like terms: 0 + 28 = 28
-5x = 28
Divide each side by '-5'.
x = -5.6
Simplifying
x = -5.6
"at least " means her score has to be more or equal 94
94≤(85+91+x)/3
it looks like correct answer is e.