Problem $03\mathrm{.}105-$ Two weights on a seesaw

NOTE: This is a multi$-$part question. Once an answer is submitted, you will be unable to return to this part.

The weights of two children sitting at ends A and $B$ of a seesaw are $68$ lb and $48$ lb $,$ respectively.

Problem $03\mathrm{.}105.$a $-$ Equivalent resultant force at a specific location

Determine the position $d$ of a third child so that the resultant of the weights of the three children will pass through $C$ if she weighs $52$

lb$.$

The position $d$ of the third child is

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