Question 765583
Basic relationship is {money}/{quantity}={moneyperquantity}


{{{(30*3+h*2)/(30+h)=2.50}}}
h is the number of ounces of the $2 per ounce herbs to use.  Adding h increases the amount of money of the blend only because it increases the amount of the blend.  The amount h is less price than the given $3 per ounce herbs; so the unit price decreases. 
SOLVE FOR h.


{{{30*3+2h=2.50(h+30)}}}
{{{15*3+h=1.25(h+30)}}}
{{{45+h=1.25h+37.5}}}
{{{45-37.5=0.25h}}}
{{{12.5=0.25h}}} ____________then just multiply by 4,
{{{h=4*(12.5)}}}
{{{h=50}}}