Question 819880
H=16
T=13.20
L=12
M=5
u = how much of the L priced cheese
v = how much of the H priced cheese


{{{u+v=M}}}
and
{{{(Lu+Hv)/M=T}}}


That is a system of equations in the unknown variables, u and v.
Solve the system for u and v, and you will have essentially solved any two part mixture problem which fits this form.  This is like a concentration-mixture problem, but here, the concentration is as DOLLARS PER KILOGRAM.  Think of the cheeses as containing dollars.