I NEED THIS ASAP!!

Mr. Williams is struggling in German and really wants to do well fourth quarter so that his overall average for the school year is a 65%. First quarter he earned a 58%, second quarter he earned a 68%, and third quarter he earned a 67%. What grade must Mr. Williams earn fourth quarter to have an overall average of 65% for the four quarters?

65%
66%
67%
68%

65%

If you look at it its the only number in the center of all the numbers if you round properly

x =±sqrt(1/3)

step-by-step explanation:

x+4/6x=1/x

multiply each side by 6x to get rid of the fractions

6x*(x+4/6x)=1/x*6x

distribute

6x^2 +4 = 6

subtract 4 from each side

6x^2 +4-4 = 6-4

6x^2 =2

divide by 6

6x^2/6 = 2/6

x^2 = 1/3

take the square root of each side

sqrt(x^2) = ±sqrt(1/3)

x =±sqrt(1/3)