Parakeet is a term for any one of a large number of unrelated small to medium sized species of parrot, that generally have long tail feathers. Older spellings still sometimes encountered are paroquet or paraquet. The term Grass Parakeet (or Grasskeet) refers to a large number of small Australian parakeets native to grasslands such as Neophema and Princess Parrot. The Australian rosellas are also parakeets. Many of the smaller, long-tailed species of lories may be referred to as lorikeets. The Budgerigar Parakeet, also known as 'Budgie' or English Parakeet, (Melopsittacus undulatus) is probably the most common Parakeet. The male can be distinguished from the female after about three months, when it first molts. With most color morphs, if the cere is brown or pinkish, the bird is female. If the cere is a bright blue, the bird is a male. In some breeds, however, the male may have a pinkish-purple cere and the female may have a pale blue, beige or white cere.
Contributions by Snowmanradio, Ianmartinez, and Curiousdiana.
You can solve using the system of linear equations b+d=15 and 2b+4d=50.