rate time distance
UPSTR r-c d
DOWNSTR r+c d
Total T
Three unknown variables but two of them can be eliminated through use of the common, simple, uniform travel rate rule. Best way for this is use the relationship and fill-in the cells of up & down stream times.
rate time distance
UPSTR r-c d
DOWNSTR r+c d
Total T
The time sum equation has ONLY ONE UNKNOWN variable, and it is the variable being asked to be solved, which is c.
THIS IS THE EQUATION TO SETUP FROM ANALYZING THE PROBLEM:
Solve this equation for c.
THE ANSWER IS WHAT IS OBTAINED WHEN THE EQUATION IS SOLVED FOR c.
Once c is solved in symbols, substitute the given values to find the value for c.