The restaurant is making a 200% profit when it sells a bowl for 30. If the bowl cost 15 to make it would be making a 100% profit. The bowls must cost 10 to make.
10 x200%profit + 10 cost = 30
10 bowls cost 100 to make so 100= 30 +50 +potatoes = 80 + potatoes 20 = potatoes (for 10 bowls) $2 = cost of potatoes per bowl.
~jc
