Which is a correct two column proof. Given <4 and

The initial statement is: QS = SU (1)

QR = TU (2)

We have to probe that: RS = ST

Take the expression (1) : QS = SU

We multiply both sides by R (QS) R = (SU) R

But (QS) R = S (QR) Then: S (QR) = (SU) R (3)

From the expression (2) : QR = TU. Then, substituting it in to expression (3):

S (TU) = (SU) R (4)

But S (TU) = (ST) U and (SU) R = (RS) U

Then, the expression (4) can be re-written as:

(ST) U = (RS) U

Eliminating U from both sides you have: (ST) = (RS) The proof is done.