$\"\"$

The word $\"\"$ 5 is to 7 $\"\"$ represents the expression $\"\"$ .

The word $\"\"$ as $\"\"$ means equal and its symbol $\"\"$ .

The word $\"\"$ a is to 49 $\"\"$ represents the expression $\"\"$ .

The word $\"\"$ 5 is to 7 as a is to 49 $\"\"$ represents the proportion $\"\"$ . $\"\"$

The proportion is $\"\"$ .

Multiply each side by $\"\"$ .

$\"\"$

Cancel common terms.

$\"\"$

$\"\"$ . $\"\"$

The value of $\"\"$ .