Question

Which property allows you to state if m4 + m5 = 59°, and m4 = 20°, then 20° + m5 = 59°??

Answer 1

The answer will be “ substitute ” because you replace angle 4 with 20°
Furthermore,
20°+m5=59°
Subtract 20° for both side
20°-20°+m5=59°-20°
m5=39°. As a result, substitute is the final answer. Hope it help!

Answer 2

Answer: Substitution Property

Think of "substitute" as in replacement. For example, your substitute teacher is a (temporary) replacement for your current teacher. In this case, we're replacing "m4" with "20 degrees".