The mean is found by dividing the sum of all terms by the number of terms present in the set.
Set up the equation:

The mean of this sequence is
5.
Answer:
x=-2
do your box method and find what multiplies to C and adds to B
to check your answer substitute x with what x=
I think Lettuce leaf but it isn't clear what you're asking.
Since the angles are equal, the sides will be equal. Set 19=3x-2 and solve. Add 2 to both sides and get 3x=21, divide both sides by three and x=7.