The mass of a certain 10k gold necklace is 18 grams. how many grams of gold are in the necklace?

Given

The mass of a certain 10k gold necklace is 18 grams.

Find out  how many grams of gold are in the necklace.

To proof

let us assume that the gold in the  necklace be x.

As given in the question

10k gold necklace i.e   gold necklace is made up  of the various elements with the gold.

10k gold necklace is 18 grams.

As pure gold is of the 24k.

than the equation becomes

solving

x =7.5 gram

7.5 grams of gold are in the necklace .

Hence proved