In a box of coloured pencils 1/6 are blue, 5/12 are green, 1/3 are red and the remainder of 108 are yellow. How many pencil are in the box?

Answer 1

1/6 = 2/12
5/12 = 5/12
1/3 = 4/12

2/12 + 5/12 + 4/12 = 11/12
so
1/12 = yellow

Answer 2

X pencils in the box.
x/6 + 5x/12 + x/3 + 108 = X.
2x/12 + 5x/12 + 4x/12 + 108 = X,
11x/12 + 108 = X,
X = 1296.