Who can help me with analog signal problems?

I’ve been trying to solve these two questions for days and still haven’t found the correct solution to these questions. Can someone help me or give me advice to find the correct solution:

1) A signal has passed through three cascaded amplifiers, each with a 4 dB gain. What is the total gain? how much was the signal amplified?

2) A signal has a wavelength of 1 Micrometer in air. How far can the front of the wave travel during 1000 periods?