What is the missing statement in step 3 of the proof?

m1 = m2

m1 + m2 = 90°

m2 = m3

m2 + m3 = 180°

Given that 1 is complementary to 2 and 2 is complementary to 3.

The prove that m1 = m3 is given as follows:

Statements Reasons

<1 is comp. to <2 Given

<2 is comp. to <3 Given

m<1 + m<2 = 90° Defenition of complementary
m<1 = 90° - m<2 Subtraction equality prop.

m<2 + m<3 = 90° Definition of complementary
m<3 = 90° - m<2 Subtraction equality prop.

m<1 = m<3 Transitivity property

Therefore, the missing statement in step 3 of the proof is m1 + m2 = 90°