$\"\"$

The slope m of a non vertical line through any two points is given by,

$\"\"$

Substitute $\"\"$ in rate of change

formula.

$\"\"$ \ \ $\"\"$ (Subtract: 8 – 4 = 4)

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

According to addition property of equality: If a = b then a + c = b + c.

$\"\"$ (Add 3 to each side)

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

$\"\"$ (Add: 3 + 3 = 6)

$\"\"$

The value of $\"\"$ .