Question

Can someone please help me with this?
proofs

Answer 1

Am I correct in assuming that the actual question here is:

What is the reason for D?

You seem to have all the other steps for the proof in place.

Answer 2

Yes, that is the real question on the assignment, but I'm having trouble understanding proofs itself:(

Answer 3

I think its called the transitive property of equality. We don't put a label to it in the UK. I thinks its a US thing.

Answer 4

What specifically are you having trouble with? Did you need a name for the property used like welshfella gave? Or do you need something else?

Answer 5

m<DBE was subtracted from both sides of the equation to give the last line of the proof.

The reason is the Subtraction Property of Equality.
@quickstudent