Originally Posted by HeSmellsLikeSmoke
Take the ingredients of batch A and list them. This equals 3 cups. Take the ingredients of batch B and multiple them by 1.2 then list them. This makes 1 1/2 cups. Add the amounts listed in A to the amounts listed in B and add them together. The result will be 4 1/2 cups of your new batch C.
Little correction. You forgot step 3. Need to first multiply the ingredients of A by 2 and not multiply the ones for B. Will end up with 7 1/4 cups of the new batch C.