X to 7 divided by x to the 9 please answer this :)

The decibel level of sound is 50 db greater on a busy street than in a quiet room where the intensity of sound is watt/m2. the level of sound in the quiet room is db, and the intensity of sound in the busy street is watt/m2. use the formula , where is the sound level in decibels, i is the intensity of sound, and is the smallest sound intensity that can be heard by the human ear (roughly equal to watts/m2).

What value of x is in the solution set of 4x - 12 s 16 + 8x? -10 -9 -8 -7

Table which ratio is equivalent to 3: 7? 6: 7 3: 21 24: 56 15: 30