Question 1002837
<b>*</b> Let x be the mass in kilograms of the pure, 100% peat moss to add.


Equation for the resulting 15% peat moss in mixture
{{{(100*12+x*100)/(x+100)=15}}}


Equation for the resulting 15% vermiculite in mixture
{{{100*6/(x+100)=15}}}
The trouble here is adding x kilograms of peat moss will only DILUTE the
concentration of vermiculite, so the problem description WILL NOT WORK and therefore
has NO SOLUTION.



<b>*</b>  The real question is, how much peat moss AND how much vermiculite must be added to reach 15% for each of them?


VARIABLES:  x for peat moss, y for vermiculite.


The peat moss & vermiculite system of equations will be
{{{system((100*12+x*100)/(x+y+100)=15,(100*6+y*100)/(x+y+100)=15)}}}


Now, if you can solve that system for x and y, you will be all set.  Most important is to be able to formulate those equations of the system.