Plz help me with thid question, I'm so confused

And employee salary increased by $4500 which represents a 15% raise what is the rate of the increase

Nell has a sales clerk job that pays $12 per hour for regular gas work hours. she gets double time for any hours over 40 that she works in a week. how many hours did nell work if her weekly pay was $744

What is the value of the expression below? (81^2)^1/8