Which expression is equivalent to (c-2d)(3c-2d)

Need on this one asap im almost done with this subject

Arefrigeration system at your company uses temperature sensors fixed to read celsius (°c) values, but the system operators in your control room understand only the fahrenheit scale. you have been asked to make a fahrenheit (°f) label for the high temperature alarm, which is set to ring whenever the system temperature rises above –10°c. what fahrenheit value should you write on the label

Perry observes the opposite parallel walls of a room in how many lines do the plains containing the walls intersect