Question 475334
Here's a decent explanation for you I found on the web.
<a href = "http://en.allexperts.com/q/Geometry-2060/law-detachment-syllogism.htm" target = "_blank">http://en.allexperts.com/q/Geometry-2060/law-detachment-syllogism.htm</a>
The answer to your question is the Law of Detachment.
That law states that:
p->q
p is true therefore q has to be true.