Question

What is half metre rule?

Answer 1

Half meter rule is a ruler whose length is half meters. I had solved the question taking length as 1 m. So accordingly the solution will change as follows -
$W\times (29-25)=20\times (50-29)$
$\Rightarrow W\times 4=20\times 21$
$\therefore W=\frac{20\times 21}{4}=105gf$