The length of pencil A is 5 cm
Solution:
Let the length of pencil A be "x"
Let the length of pencil B be "y"
Let the length of pencil C be "z"
The total length of pencils A, B and C is 29 cm
Therefore,
length of pencil A + length of pencil B + length of pencil C = 29
x + y + z = 29 ------------ eqn 1
Pencil A is 11 cm shorter then pencil B
x = y - 11 ------- eqn 2
Pencil B is twice as long a pencil C
y = 2z
[tex]z = \frac{y}{2}[/tex] ------ eqn 3
Substitute eqn 2 and eqn 3 in eqn 1
[tex]y - 11 + y + \frac{y}{2} = 29\\\\2y + \frac{y}{2} = 29 + 11\\\\\frac{4y+y}{2} = 40\\\\5y = 80\\\\y = 16[/tex]
Substitute y = 16 in eqn 2
x = 16 - 11
x = 5
Thus length of pencil A is 5 cm