Answer:
see attached
Step-by-step explanation:
When there is a lot of repetitive calculation, I like to let a spreadsheet do it.
Of course, the quantities are ...
You can enter the fractions directly in the spreadsheet (=12/16, for example), and it will do the calculation. The recipe cost is the product of recipe quantity and unit cost.
The total recipe cost and per-portion calculations should be obvious: the total is the sum of ingredient costs; the per-portion cost is that total divided by 50 portions. The spreadsheet has been set to round to 2 decimal places (cents).