So we are given that eight, nine, five are gray wingless, 905 are black wing but 110 are gray wings and 90 are black wingless. To make a total of if we sum these up, we obtain 2000 offspring. So the question is what is the recombination frequency between the two traits the color traits and that wing type trait? And to find the recombination frequency, also known as percent recombination what we basically do is we sum up all the offspring that are recombinant. So 110 plus 90. So 110 plus 90, this is the total number of offspring that are recombinant and we divide it by the total number of offspring.