A rectangular field is to be fenced off on three sides with the fourth side being the bank of a river. If the cost of the fence is $8 per foot for the two ends and $12 per foot for the side parallel to the river, what are the dimensions of the largest rectangle that can be enclosed with $3840 worth of fence

120 x 160

Step-by-step explanation:

If the length of the two ends is x foot per end, and the length of the parallel side is y foot, you can write the following equations:

16x + 12y = 3840

area = x * y

Simplify and rewrite the first and combine with second:

y = 320 - 4/3x

area = 320x - 4/3x²

Now you have a quadratic equation of which you want the maximum.

[calculation omitted]

The top is reached for x = 120 and y=160

The area will then be 19,200 ft²

b) well because you get well

answer set (b) 0.5, 3/4 80% is in order from least to greatest.  

step-by-step explanation:

in order to compare rational numbers to each other, it is much easier if they are in the same form.   typically, the best form in which to evaluate rational numbers is in decimals.   in order to convert a percent to a decimal, you would divide the given percentage by 100.   you can also accomplish the conversion by moving the decimal point over two places to the left.   for example, the decimal value of 80% is 80/100, or 0.8.   in order to convert a fraction to a decimal, you need to divide the numerator by the denominator.   for example, 3/4 is 0.75.   so, for choice (b) 0.5 3/4 (0.75), 80% (0.8) is the only choice in which the numbers are in order from least to greatest.