What what are the rules for addition and subtraction with numbers in scientific notation?

Can someone me i’m confused. will give brainliest and a whole bunch of points

Suppose that an airline uses a seat width of 16.516.5 in. assume men have hip breadths that are normally distributed with a mean of 14.414.4 in. and a standard deviation of 0.90.9 in. complete parts (a) through (c) below. (a) find the probability that if an individual man is randomly selected, his hip breadth will be greater than 16.516.5 in. the probability is nothing. (round to four decimal places as needed.)

If olu is twice as old as funmi if the sum of their ages is 60 how old is olu