[tex]\bf \begin{array}{lccclll}
&\stackrel{lbs}{amount}&\stackrel{unit}{cost}&\stackrel{total}{value}\\
&------&------&------\\
Raisins&11&2.30&25.3\\
Peanuts&p&4.50&4.5p\\
------&------&------&------\\
mixture&m&3.29&3.29m
\end{array}[/tex]
we know that, the mixture amount is the sum of 11 + p, or 11 + p = m.
we also know that, the total value is also a sum of 25.3 + 4.5p = 3.29m.
[tex]\bf \begin{cases}
11+p=\boxed{m}\\
25.3+4.5p=3.29m\\
----------\\
25.3+4.5p=3.29\left( \boxed{11+p} \right)
\end{cases}
\\\\\\
25.3+4.5p=36.19+3.29p\implies 1.21p=10.89\implies p=\cfrac{10.89}{1.21}
\\\\\\
p=\stackrel{lbs}{9}[/tex]
