How long (in seconds) does it take for a radio wave of frequency 8.94 × 106 s–1 to reach Mars?

As space exploration increases, means of communication with humans and probes on other planets are being developed. How long (in seconds) does it take for a radio wave of frequency 8.94 × 106 s–1 to reach Mars when Mars is 8.2 × 107 km from Earth?