Help? Fast? Picture above is the question

The cost of using a service is $0.25 per min. what equation correctly represents the total cost c, in dollars, for d days of use?

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

Darragh has a golden eagle coin in his collection with a mass of 13.551\,\text{g}13.551g. an uncirculated golden eagle coin has a mass of 13.714\,\text{g}13.714g.