Answer:
3 g
Step-by-step explanation:
You want to know the mass of thyme that must be added to 12 g of a spice mix that is 25% thyme in order to make it 40% thyme.
Let t represent the amount of added thyme (in grams). The amount of thyme in the augmented mix is ...
0.25(12) + t = 0.40(12 +t)
Simplifying the equation gives ...
3 +t = 4.8 +0.40t
0.6t = 1.8 . . . . . . . . . subtract 0.40t +3
t = 3 . . . . . . . . . . . divide by 0.6
3 grams of thyme must be added to the mix.
