Which incondicional is not a good definition

a ray is a bisector of an angle if and only if it splits the angle into two angles

a whole number is odd if and only if the number is not divisible by two

an angle is straight if and only if its measure is 180

a whole number is even if and only if it is divisible by two

Afactory buys 10% of its components from suppliers b and the rest from supplier c. it is known that 6% of the components it buys are faulty. of the components brought from suppliers a,9% are faulty and of the components bought from suppliers b, 3% are faulty. find the percentage of components bought from supplier c that are faulty.