$\"\"$

According to Means-extremes Property of proportion: If $\"\"$ , then ad = bc.

$\"\"$ (Cross products)

$\"\"$ (Distributive proeperty: a (b+c) = ab + ac) $\"\"$

According to Addition property of equality; if a = b than a + c = b + c.

$\"\"$ (Subtract 10 from each side)

$\"\"$ (Additive inverse proerpty: $\"\"$ )

$\"\"$ (Add: $\"\"$ )

$\"\"$ (Divide each side by 5)

$\"\"$ (Cancel common terms)

$\"\"$ (Divide: $\"\"$ ) $\"\"$

The value of $\"\"$ .