$\"\"$

\

Find the speed of boat which is in travel north side,

\

$\"\"$

\

$\"\"$ (Substitute $\"\"$ and $\"\"$ )

\

$\"\"$ (Simplify)

\

Find the speed of boat which is in travel west side,

\

$\"\"$

\

$\"\"$ (Substitute $\"\"$ and $\"\"$ )

\

$\"\"$ (Simplify)

\

$\"\"$

\

Find the average speed of boat by using the formula $\"\"$ .

\

$\"\"$ (Substitute: $\"\"$ and $\"\"$ )

\

$\"\"$ (Simplify)

\

$\"\"$ .

\

$\"\"$

\

The avarage speed of the boat is $\"\"$ .