The table above shows that the scores of a group of students in a test. If the average score is 3.5, find the value of x

The table above shows that the scores of a group of students in a test. If the average score is 3.5, find the value of x

Answer Details

$mean=\frac{60+5x}{18+x}3.5=\frac{60+5x}{18+x}\frac{7}{2}=\frac{60+5x}{18+x}$
7(18+x) = 2(60+5x)
126 + 7x = 120 + 10x
10x - 7x = 126 - 120
3x = 6
x = 2