Answer
$22.5$ pounds of cashews
Work Step by Step
Let
$x=$ the number of pounds of cashews.
$y=$ the number of pounds of the whole mixture.
Given: $\left\{\begin{array}{lll}
x+30=y & ...amounts & (1)\\
5x+1.5(30)=3y & ...revenue & (2)
\end{array}\right.$
Substitute y in (2)
$5x+1.5(30)=3(x+30)$
$5x+45=3x+90$
$5x-3x=90-45$
$2x=45$
$x=22.5$ pounds.
(we don't need y, which is $22.5+30=52.5)$
