SOLUTION: Three kilograms of grass seed A contains 5% herbicide. A different type of grass seed, grass seed B which contains 20% herbicide, will be mixed with the 3 kilograms of grass seed A

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Question 998508: Three kilograms of grass seed A contains 5% herbicide. A different type of grass seed, grass seed B which contains 20% herbicide, will be mixed with the 3 kilograms of grass seed A. How much grass seed B should be added to the 3 kilograms of grass seed A so that the resulting mixture contains 15% herbicide?
Answer by fractalier(6550) About Me  (Show Source):
You can put this solution on YOUR website!
Let x be the amount of B needed. The setup looks like this:
3(.05) + x(.20) = (3+x)(.15)
.15 + .2x = .45 + .15x
Collect like terms and get
.05x = .3
x = 6 kg