Which of the following is an example of perpendicular lines?

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).

Do,h = (7, 9) (14, 18) the scale factor is

Use the elimination method to solve the systems of equations.choose the correct ordered pair. 7x+4y=39