The estimate of the problem would be 1/4 because 6/8- 1/2 you would get 1/4.
~Good Luck!~
According to my research, And I would take this with a grain of salt since I am not a insurance rep . You can earn up to four quarters of coverage each year. In order to be fully insured for Social Security Disability purposes, you must have earned at least one quarter of coverage per year for each year since you turned 21 years old. A minimum of six quarters of coverage is needed to be fully insured at any age so maybe Six quarters, at least according to SSD .
Hope I helped or shed some light !.
Answer: 
Step-by-step explanation:
Given
The ratio of mixture of sand and cement is 5:3
If the total volume of mixture is 
Suppose there is 5x and 3x cubic centimeter of sand and cement respectively i.e.
Sand 
So, there is of sand in the mixture
W=width of the pasture, and
<span>320000/w=length (parallel to river) </span>
<span>F=twice width + length </span>
<span>=2w + 320000/w </span>
<span>Find derivative of F with respect to w and equate to zero to find w. </span>
<span>i.e. </span>
<span>Solve for w in </span>
<span>dF/dw=0
hope it helps</span>
