Answer:
Therefore,

Step-by-step explanation:
Given:
![A=\left[\begin{array}{ccc}3&6&9\\2&4&8\\\end{array}\right]](https://tex.z-dn.net/?f=A%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D3%266%269%5C%5C2%264%268%5C%5C%5Cend%7Barray%7D%5Cright%5D)
To Find:
a₂₁ = ?
Solution:
Let,
![A=\left[\begin{array}{ccc}a_{11}&a_{12}&a_{13}\\a_{21}&a_{22}&a_{23}\\\end{array}\right]](https://tex.z-dn.net/?f=A%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7Da_%7B11%7D%26a_%7B12%7D%26a_%7B13%7D%5C%5Ca_%7B21%7D%26a_%7B22%7D%26a_%7B23%7D%5C%5C%5Cend%7Barray%7D%5Cright%5D)
We require ' a₂₁ ' i.e Second Row First Column Element
So on Comparing we get
∴ 
Therefore,

Felipe subtract 3x from both side to get rid of x on one side. Ik this isn’t part of the answer but the correct way to do this would be to subtract 2x from each side after adding 8 to each side of the equation
(1,4) this is because the flip over y axis does not touch the y value but gives the opposite of the x value
Answer:
The measures of the angles are 150° and 30°.
Step-by-step explanation:
Let x and y represent the measures of the angles, with x representing the larger angle.
x + y = 180 . . . . . . the two angles are supplementary
x = 90 + 2y . . . . . one is 90° more than twice the other
___
Substituting the expression given by the second equation into the first, we have ...
(90 +2y) +y = 180
3y = 90 . . . . . . . . . . collect terms, subtract 90
y = 30 . . . . . . . . . . . divide by the coefficient of y
x = 180 -y = 150
The measures of the angles are 150° and 30°.