What is the mode (math)?​

Sketch one cycle if the cosine function y=2cos2theta

Tom is the deli manager at a grocery store. he needs to schedule employee to staff the deli department for no more that 260 person-hours per week. tom has one part-time employee who works 20 person-hours per week. each full-time employee works 40 person-hours per week. write and inequality to determine n, the number of full-time employees tom may schedule, so that his employees work on more than 260 person-hours per week. graph the solution set to this inequality.

What is the missing reason in the proof? segment addition congruent segments theorem transitive property of equality subtraction property of equality?