It would take him 5 weeks. why?
7.89*20= $156 per week
156*5 weeks= $780
5m + 4m = 72
Combine like terms.
9m = 72
Divide both sides by 9.
m = 8
Answer:
She bought 8 books
Step-by-step explanation:
8.96/1.12
Considering the given system of equations, it is found that:

<h3>What is a system of equations?</h3>
A system of equations is when two or more variables are related, and equations are built to find the values of each variable.
In this problem, the system is:
-8x+y=-6
3x-2y=-1
In matrix form, it is given by:
![\left[\begin{array}{cc}-8&1\\3&-2\end{array}\right]\left[\begin{array}{c}x\\y\end{array}\right] = \left[\begin{array}{c}-6\\-1\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7D-8%261%5C%5C3%26-2%5Cend%7Barray%7D%5Cright%5D%5Cleft%5B%5Cbegin%7Barray%7D%7Bc%7Dx%5C%5Cy%5Cend%7Barray%7D%5Cright%5D%20%3D%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bc%7D-6%5C%5C-1%5Cend%7Barray%7D%5Cright%5D)
To find the matrix |Ay|, we replace the y coefficients of 1 and -2 by the results of -6 and -1, hence:

More can be learned about a system of equations at brainly.com/question/24342899
Since the measure of an angle is 12 degrees less than the measure of its supplement, then x=180-x-12 or 2x=168 or x=84 and 180-x=96. Step 4. ANSWER: The angle is 84 degrees and its supplementary angle is 96 degrees.