6) A signal travels from point A to point B. At point A, the signal power is 100 W. At point B, the power is 90 W. What is the attenuation in decibels? Show the formula for calculating decibels and then solve. 7) A signal has passed through three cascaded amplifiers, each with a 4-dB gain. What is the total gain? How much is the signal amplified? Show the formula. 8) A line has a signal-to-noise ratio of 1000 and a bandwidth of 4000. What is the maximum data rate supported by this line? Use the Shannon equation.