Explain how to use benchmarks to estimate 0.28 + 71

According to statistics a person will devote 32 years to sleeping and watching tv. the number of years sleeping will exceed the number of years watching tv by 18. over a lifetime, how many years will the person spend on each of these activities

How can you find the mean absolute deviation (mad) for this set of data?

Let x = a + bi and y = c + di and z = f + gi. which statements are true?