Lenny is baking 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? 14,28,7,21
Since the recipe calls for 2 parts borax and 2 parts washing soda for every 1 part soap flakes, the total number of cups of borax and washing soda combined needed would be 2+2 = <<2+2=4>>4 parts.
If Lenny uses 7 cups of soap flakes, then he would need 7/1= <<7/1=7>>7 cups of borax and washing soda combined. Answer: \boxed{7}.