Help please? and how should i show my work.

Solutions for 2x+7 less than or equal to 3x-5

Witch represents the inverse of the function f(x)=1/4x-12

Monitors manufactured by tsi electronics have life spans that have a normal distribution with a standard deviation of 1800 hours and a mean life span of 20,000 hours. if a monitor is selected at random, find the probability that the life span of the monitor will be more than 17,659 hours. round your answer to four decimal places.