Let the amount of pine needle in the potpourri be x oz.
Let the amount of lavender in the potpourri be y oz.
Then, from the given question it is clear that:
oz
Thus,
.....................................(Equation 1)
Now, if the cost of pine needle is $1.5/ounce then, the total cost of pine needle in the potpourri will be:
.
Likewise, the total cost of lavender in the potpourri will be 
From (Equation 1) we thus have, 
Since the total cost of the 80 oz potpourri is $200, therefore, the above information can be combined to yield:
(total cost of pine needle in the potpourri)+(total cost of lavender in the potpourri)=total cost of the potpourri




Therefore,

Thus, from (Equation 1), 
Therefore, the amount of pine needle in the potpourri is 48 oz and the amount of lavender is 32 oz