V = c * (f - f₀)/(f + f₀)
v/c = (f - f₀)/(f + f₀)
v/c = 1 - 2f₀/(f + f₀)
2f₀/(f + f₀) = 1 - v/c
2f₀/(f + f₀) = (c - v)/c
(f + f₀)/2f₀ = c/(c - v)
(f + f₀)/f₀ = 2c/(c - v)
f/f₀ + 1 = 2c/(c - v)
f/f₀ = 2c/(c - v) - 1
f/f₀ = (2c - c + v)/(c - v)
f = f₀ * (c + v)/(c - v)
f = 495 * (1500 + 15)/(1500 - 15) = 505 МГц