7x + 15 = 1520
It’s $7 times the unknown number of shirts (x). Plus $15 to ship. All has to equal the total of $1,520.
![\left[\begin{array}{ccc}2&6&3\\-5&1&4\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D2%266%263%5C%5C-5%261%264%5Cend%7Barray%7D%5Cright%5D)
R1 ÷ 2 = ![\left[\begin{array}{ccc}1&3&1.5\\-5&1&4\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D1%263%261.5%5C%5C-5%261%264%5Cend%7Barray%7D%5Cright%5D)
R2 ÷ -5 = ![\left[\begin{array}{ccc}1&3&1.5\\1&-0.2&-0.8\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D1%263%261.5%5C%5C1%26-0.2%26-0.8%5Cend%7Barray%7D%5Cright%5D)
R2: R1 - R2 = ![\left[\begin{array}{ccc}1&3&1.5\\0&3.2&2.3\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D1%263%261.5%5C%5C0%263.2%262.3%5Cend%7Barray%7D%5Cright%5D)
R2 ÷ 3.2 = ![\left[\begin{array}{ccc}1&3&1.5\\0&1&0.71875\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D1%263%261.5%5C%5C0%261%260.71875%5Cend%7Barray%7D%5Cright%5D)
R1: R1 - 3R2 = ![\left[\begin{array}{ccc}1&0&0.65625\\0&1&0.71875\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D1%260%260.65625%5C%5C0%261%260.71875%5Cend%7Barray%7D%5Cright%5D)
Answer: x = 0.65625, y = 0.71875
Answer: r=1/2
Step-by-step explanation:
Y= -x and y= -1/x
Are one-one
y= -x, inverse x= -y
Identify function
hence, inverse of y= -x in y= -x
similarly in the case of y= -1/x
so option (D) I and II, only