Question

A certain drug is made from only two ingredients: compound A and compound B. There are 8 milliliters of compound A used for every 5 milliliters of compound B. If a chemist wants to make 1222 milliliters of the drug, how many milliliters of compound A are needed?

Answer 1

 3:2 ration of A to B 
so out of the 5 total parts (3+2=5), 

3/5 are chem a 
2/5 are chem b 
note this adds up to 5/5 or 100% of the final product 

so 3/5*460 = parts of soltuion that is chem A