(4⁷÷4³) ×4² pls help im being timed show steps also​

An advertising firm has an old computer that can prepare a whole mailing in 6 hours. with the of newer model the job is complete in 2 hours. how long would it take the newer model to do the job alone?

Aladder that is 20ft long is leaning against the side of a building. if the angle formed between the ladder and the ground is 75 degrees how far is the bottom of the from the base of the building?

What is the point of inflection for the function f(x)=2cos4x on the interval (0, pi/2)