Mary must average at least 30 hours of work per week during each five-week cycle to keep her health benefits. During the first four weeks of the cycle, she has worked 30, 30, 28, and 28 hours. What is the lowest amount of hours she can work in the fifth week to have a weekly average of 30 hours?

34 hours

Step-by-step explanation:

given the figures for the work are

30, 30, 28, and 28

we know that average

A= sum of values/number of values

let the fifth value be x

the number of values is now 5

given that A=30

30=30+30+28+28+x/5

cross multiply

150=116+x

x=150-116

x=34 hours

-2

7 - 9 = -2

reversed:

-2 + 9 = 7