So remember that area of a rectangle is a = bh. In this case, our sides are 2 and n - 3 (three less than unknown number) and our area is 22. Using our info, we can form the equation:
. From here we can solve for n.
Firstly, foil 2(n-3): 
Next, add 6 on both sides of the equation: 
Next, divide both sides of the equation and your answer will be 14 = n. In context, the value of the unknown number is 14 in.
To find how many ounces we need for 26, we have to find a factor of 6 and 26, find how many ounces we need for that many people, and multiply it to get it to 26 people. Since 6 and 26 are both even, we know that they both have 2 as a factor. In addition, since 6/3=2, we can divide 45 by 3 to get how many ounces of lemonade we need for 2 people - 45/3=15 ounces. In addition, since we know that 26/13=2, we need to multiply 15 by 13 to see how many ounces we need for 26 people, which is 195
4 : 28 is the same as 4/28
4/28 = 1/7
The answer is C