What is red blue and white flag with crest?

Without additional context, it's difficult to provide a specific answer as there are numerous flags that fit this description. Here are a few possibilities:

• The flag of the United Kingdom (also known as the Union Jack) features a blue field with a red diagonal cross, and a white diagonal cross overlaid on top. In the upper left quadrant is the crest of the royal coat of arms which includes a lion and a unicorn.

• The flag of the United States is commonly referred to as the "stars and stripes". It features alternating red and white stripes, with a blue field in the upper left corner containing 50 white stars. This flag does not typically include a crest.

• The flag of Russia is a tricolor featuring three horizontal stripes of white, blue, and red. In the center of the flag is the coat of arms of Russia which includes a double-headed eagle.

• The flag of France is another tricolor, with three vertical stripes of blue, white, and red. It does not include a crest.

Without more information, it's impossible to know which particular red, blue, and white flag with a crest is being referred to.