Frank solved an equation and got the result x = x. Sarah solved the same equation and got 19 = 19. Frank says that one of them is incorrect because you cannot get different results for the same equation. What would you say to Frank? If both results are indeed correct, explain how this happened.

Anut store normally sells cashews for? $4.00 per pound and peanuts for? $1.50 per pound. but at the end of the month the peanuts had not sold? well, so, in order to sell 40 pounds of? peanuts, the manager decided to mix the 40 pounds of peanuts with some cashews and sell the mixture for $2.00 per pound. how many pounds of cashews should be mixed with the peanuts to ensure no change in the? profit?