To solve the problem, we need to determine the total parts in the recipe and the ratio of borax and washing soda relative to soap flakes.
The recipe is given in parts:
- Borax: 2 parts
- Washing soda: 2 parts
- Soap flakes: 1 part
The total parts in the recipe are:
- 2 (borax) + 2 (washing soda) + 1 (soap flakes) = 5 parts in total.
Now, if Lenny uses 7 cups of soap flakes, which corresponds to 1 part, we can find out how many cups each part represents:
- Since 1 part (soap flakes) = 7 cups, each part equals 7 cups.
Next, we can calculate how much borax and washing soda Lenny needs:
- Borax: 2 parts x 7 cups/part = 14 cups
- Washing soda: 2 parts x 7 cups/part = 14 cups
Now, to find the combined total of borax and washing soda:
- Borax (14 cups) + Washing soda (14 cups) = 28 cups.
Thus, the answer is 28 cups.