The roads that connect three buildings form a right triangle. Use the image to find the distance between the library and the museum.

knowing a² + b² = c²

a = 300 yards
b = ?
c = 500 yards

so plugging into the equation gives 300² + b² = 500², solving for b 
b² = 500² - 300² 
b = √(160000 = 400 yards