$\"\"$

It is belived that about $\"\"$ of our dreams involve people that we know.

Write an expression to describe the number of dreams that feature people :

The number of dreams known is $\"\"$ .

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

The expression is $\"\"$ .

$\"\"$

Find the number of dreams include people know out of $\"\"$ dreams:

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

$\"\"$ ( $\"\"$ )

$\"\"$ (Multiply)

Therefore, the number of dreams that include people know $\"\"$ dreams out of dream is $\"\"$ dreams.

$\"\"$

a. The expression is $\"\"$ .

b. The number of dreams that include people know $\"\"$ dreams out of dream is $\"\"$ dreams.