Question 755483
This is like a mixture concentration problem in which the concentration is dollars per pound.


p for peanuts
c for cashews


{{{(9*p+11.35*c)/140=12}}} and {{{p+c=140}}}  which should be enough to start.


To continue, {{{9p+11.35c=140*12}}} and {{{c=140-p}}} so substitute,
{{{9p+11.35(140-p)=140*12}}}
{{{9p+(11.35)*140-(11.35)*p=140*12}}}
and you can continue through this to solve for p, and then go back to solve for c.