The equation f(x)=x^2−12x+45 models the number of books y sold in a bookstore x days after an award-winning author appeared at an autograph-signing reception. How many books were sold after 4 days? Keep the answer as a whole number.

Iwill give brainliest. give accurate answer, . suppose tommy walks from his home at (0, 0) to the mall at (0, 5), and then walks to a movie theater at (6, 5). after leaving the theater tommy walks to the store at (6, 0) before returning home. if each grid square represents one block, how many blocks does he walk?