16 ounces of birdseed mix contains 10% sesame seed by weight. How

much sesame seed must be added to produce a mix that is 20% sesame

seed by weight?

16 Ounces of BS contain 10% of SS which is 1.6 Ounce of SS. What they are asking is how much more SS ( already have 1.6) should be added to BS ( already have 16 ), so that SS is now 20% of BS

Based on above the eqn can be derived as

( 16 + x ) * ( 0.2 ) = 1.6 + x … where x is the extra SS we are adding

Simplifying above we get SS = 2 ounces

So now there is a total of 18 ounces of BS and 3.6 ounces of SS ( which is 20% of BS )

thank you so much!!