To identify the Property of Equality being demonstrated by the given equations, we should first identify the operation being performed.
IfXY+20=YW and XY+20=DT,
thenYW=DT.
In this case, we are given three equations.
XY+20= YW
XY+20= DT
⇕
YW= DT
This demonstrates the Substitution Property of Equality.
