Lenny is making his own laundry soap. The recipe calls for 2 parts borax, 2 parts washing soda, and 1 part soap flakes. If Lenny uses 7 cups of soap flakes, how many cups of borax and washing soda combined does he need?(1 point) Responses 21 cups 21 cups 7 cups 7 cups 28 cups 28 cups 14 cups
The recipe calls for 2 parts borax and 2 parts washing soda, so Lenny needs (2 + 2) = <<2+2=4>>4 parts in total.
Since there are 7 cups of soap flakes, each part is equal to 7/1 = 7 cups.
Therefore, Lenny needs 4 parts x 7 cups = <<4*7=28>>28 cups of borax and washing soda combined. Answer: \boxed{28}.