The answer would be A. 21 because 21/7 would equal 3
Answer:
245/999
Step-by-step explanation:
0.245bar = n
1000 n - n = 245
999n = 245
n = 245/999
![\left[ \begin{matrix} 2 & a \\ -1 & -2 \end{matrix} \right] + \left[ \begin{matrix} b & 4 \\ -2 & 1 \end{matrix} \right]](https://tex.z-dn.net/?f=%5Cleft%5B%20%5Cbegin%7Bmatrix%7D%202%20%26%20a%20%5C%5C%20-1%20%26%20-2%20%5Cend%7Bmatrix%7D%20%5Cright%5D%20%2B%20%5Cleft%5B%20%5Cbegin%7Bmatrix%7D%20b%20%26%204%20%5C%5C%20-2%20%26%201%20%5Cend%7Bmatrix%7D%20%5Cright%5D)
This addition of matrices can be combined into one matrix.
To add matrices, add the corresponding components of each matrix.
After adding, we'll have the following
![\left[ \begin{matrix} 2+b & a+4 \\ -3 & -1 \end{matrix} \right]](https://tex.z-dn.net/?f=%20%5Cleft%5B%20%5Cbegin%7Bmatrix%7D%202%2Bb%20%26%20a%2B4%20%5C%5C%20-3%20%26%20-1%20%5Cend%7Bmatrix%7D%20%5Cright%5D%20)
This matrix should be equal to the matrix on the right-hand side of the equation. This means that each corresponding component of this matrix and the other matrix should be equivalent.
This means that

AND

Solving these one-step equations will give the values of a = -4 and b = -1. That's answer choice D.
Answer:
x=8 y=4
Step-by-step explanation:
x=12-y
12-y-y=4
-2y=-8
y=4
x=12-y
x=12-4
x=8
9x-7= 29
9x-7+7= 29+7
9x= 36
Divide by 9 for 9x and 36
9x/9= 36/9
x= 4
Check answer by using substitution method
9x-7= 29
9(4)-7=29
36-7= 29
29= 29
Answer is x=4 (second choice)