communication principal- FM detector: slope detector

A slope detector has a filter with straight-line roll-off slopes in its amplitude (dB) characteristics - “dB versus frequency”. The output of the filter at these slopes ranges from 0 dB at the nominal center frequency to –20 dB at 5000 Hz above or below the center frequency. If the zero dB signal is 1 V, what is the slope detector output in volts at 2500 Hz off the center frequency? What will the detector output at 5000 Hz off the center frequency?