A spice mixture is 25% thyme. How many grams of thyme must be added to 12 g of the mixture to increase the thyme content to 40%?

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Answer 1 · 2017-02-25T16:39:25

We must add $3$ g of thyme

As spice mixture is $25%$ thyme, in $12$ g of the mixture

we have $12xx25/100=3$ g of thyme.

If we add $x$ g of thyme,

we have $x+3$ g of thyme and $12+x$ g of mixture

but this should be $40%=40/100$

Hence $(x+3)/(12+x)=40/100$

i.e. $100x+300=480+40x$

or $100x-40x=480-300$

or $60x=180$

i.e. $x=180/60=3$

Hence, we must add $3$ g of thyme

then we have $6$ g of thyme in $15$ g of mixture.