AA large eggs have an average weight of 2 oz.
Then, in a whole dozens you have 24 oz.
In order to determine how many eggs do you need, you consider that the angel cake formula requires 3 lb 7 oz of egg whites, furthermore, you consider that 1 lb = 16 oz. Then, the total weight in oz units of the required eggs is:
3 lb + 7 oz = 3 (16 oz) + 7 oz = 48 oz + 7 oz = 55 oz
Now, you take into account that only 53% of an egg is egg white. You calculate the equivalent weight of this percentage, as follow:
0.53(2 oz) = 1.06 oz
then 1.06 oz is egg white.
Finally, tou calculate the quotient between the weight of the required egg whites (55 oz) between the weight of egg white for one egg (1.06z):
55/1.06 = 51.88 (you approximate to the higher whole number)
55/1.06 ≈ 52
Hence, you need 52 eggs to make the angel cake. This result in dozens is:
52/12 = 4.33 ≈ 4.5 = 4 1/2
Hence, you required of aproximately 4 and one half dozens