Lou wants to make a coffee mixture to sell. he is going to mix sumatra coffee which costs $2.50 per pound with columbian coffee which costs $3.75 per pound. he wants to male 50 pounds of mix and he wants the cost of the mix to be $3.35 per pound. how many pound of each will he need?

To answer this question you need to create 2 equations:
S+C=50
2.50S+3.75C=3.35*(50) 
S=50-C -so now you can plug in S into the second equation
2.50*(50-C)+3.75C=167.5
Now you just need to solve this equation, the final answer will be 34 pounds of colombian coffee and 16 pounds of sumatra coffee 

50 % is the answer !