I need some help please I have done a and b but need help with c and d

Find all the values of x that make 0.1x + 0.25(102 - x) < 17.10 true.

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.

Gabrielle's age is two times mikhail's age. the sum of their ages is 84. what is mikhail's age?