When you do (f+g)(x), all you have to do is take both functions and add them to each other. It should look like this when you set it up:

Then just add like terms and you should get:

Hope this helped.
Mean is the sum of values divided by the count of values.
The sum of values is 1,235.
There are 9 values.
1235/9 = 137.22
It is a good idea to get familiar with the operation of your calculator. If you're going to use on-line resources to work problems like this, you can make use of any of several good on-line calculators. Google and Bing search boxes will do calculations for you while observing all the rules of the Order of Operations.
The result of this computation is a number that begins 2.56.... Since the hundredths digit is more than 4, the tenths digit is rounded to the next higher value, from 5 to 6.
Rounded to tenths, 2.1√1.488 = 2.6
The gcf of 90 and 72 is 18, so i divided both of them by 18 and i got 4 and 5, in total he would 9 pieces of wood