Do problem 6.2.5 on page 216.
Assume *A'* is upper-triangular and has been augmented with *b'*
as its final column,
and that it is indexed in the expected way
(e.g. *A'[i,j]* is the entry in row *i* and column *j*).
The solution should be placed in a vector *x*
(e.g. *x[1]* will store the value of *x*_{1}, etc.)

Hint: Pay careful attention to how you solved systems with 3 or 4 variables. Which variable did you solve for first?
How did you find each of the remaining variables? You should realize
that the process you followed can be captured by a simple formula.

Do not forget to analyze your algorithm.
(Hint: You will need to express it using one or more sums which you will
then need to simplify.)