Quandaries
and Queries 

two known values product # 1 = 60% protein product # 2 = 80% protein How much of the #2 product would I need to add to the # 1 product to
create a third product of 65% 

Hi Ray, You didn't say how much of product #1 you have so I am going to assume you have one unit of product #1. To it you want to add an unknown quantity of product #2. Suppose the unknown quantity id x units. Hence when you add them you have (1 + x) units of the mixture.
Thus
Solve for x. Penny 

