What is 20+40*5? show your work

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 a rational number between 9.5 and 9.7

Which describes the difference between the graph of f(x)=x^2 and g(x)=-(x^2-2)