According to the graph what is the value of the constant in the equation below

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 is the lcm of 16 and 40 ? 24 and 40 ?

Solve each quadratic equation by factoring and using the zero product property. x^2 - 8x + 30 = 3x