`3+4=?`

If (3a + 4b)/(3c + 4d) = (3a-4b)/(3c-4d) , then

How many 4's are there in the following series which is immediately followed by 5 but not immediately preceded by 3 ? 5 4 4 3 3 4 5 4 5 5 3 4 4 3 4 5 4 3 3 5 4 5 4 3 5 4 4 3 5 4 1) 0 2) 1 3) 2 4) 3 5) More than three

(-4/3)xx(-4/3)xx(-4/3)xx(-4/3)xx(-4/3)