Question

1/8 part of a pencil is black one by two part of the remaining is white if the remaining part is blue and the length of this blue part is 3 1/2 cm find the length of the pencil

Answer 1

let total length of the pencil=A ,

then
black part=A/8,

remain part=7A/8,

white part=1/2 × 7A/8,

=7A/16,

now remaining part=blue part=7A/8 - 7A/16,

=(14A-7A)/16,

blue part=7A/16,

now according to the question, we have

7A/16 = 7/2 cm,

then
A=16/2=8cm

Answer 2

${\boxed {\pink {\bigstar{answer}}}}$

$\small \purple{let \: assume \: length \: of \: the \: pencil \: is \: x}$

$\small \red{as \: per \: que. \: portion(length) \: of \: black \: in \: pencil} = \frac{x}{8}$

$remaining \: portion = x - \frac{x}{8} = \frac{7x}{8}$

$so \: white \: portion = \frac{1}{2} \times \frac{7x}{8} = \frac{7x}{16}$

$so \: remaining \: portion = \frac{7x}{8} - \frac{7x}{16} = \frac{7x}{16}$

$\green{as \: per \: question}$

$\frac{7x}{10} = 3.5$

${\fcolorbox{pink}{white}{x = 8cm}}$

HOPE IT'S HELPS YOU ❣️