Answer:
the answer to your question is
2n + 20
519/6=86.5
915/7=130.7142
439/7=62.7142
812/9=90.2222
so i think its the 1st on but i may be wrong.
To find the cofactor of
![A=\left[\begin{array}{ccc}7&5&3\\-7&4&-1\\-8&2&1\end{array}\right]](https://tex.z-dn.net/?f=A%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D7%265%263%5C%5C-7%264%26-1%5C%5C-8%262%261%5Cend%7Barray%7D%5Cright%5D)
We cross out the Row and columns of the respective entries and find the determinant of the remaining
matrix with the alternating signs.
























Therefore in increasing order, we have;

Ration of minutes of television to commercial is 35:7.8
3 hours and 50 minutes is 230 minutes
230:X
35:7.8
Multiply both sides by 6.6
X=51.5 minutes
There is about 51.5 minutes of commercials