<span>The equation is not quadratic in for because it cannot be written as a second degree polynomial</span>
You may remember the two way relative frequency table where each entry in the table is divided by a total from the table. When each cell is divided by the table total (in this case 240), you get a two way whole table relative frequency. (There are also row and column relative frequency tables.)
Answer:
9. This is because you have to add 13 to -4, which gives you positive 9. Hope this helped!