What is the speed of sound in air with a temperature of 25 degrees Celsius?

The graph describes the motion of an object. the object moves with from a to b. it from b to c. it moves with from c to d.

Unpolarized light of intensity i_0=750w/m^2 is incident upon two polarizers. after passing through both polarizers the intensity is i_2=280w/m^2. (a) what is the intensity of the light after it passes through the first polarizer in w/m^2? (b) write an equation for the angle between the polarizers in terms of the initial (i_0) and final (i_2) intensities. (c) find the angle between the polarizers in degrees.

Ineed the answer to question 1 , i’m desperate