Question

what is the next step in the given proof?
1.<1 and<2 are both complementary to<3 : given
2.m<1=m<3=90 m<2=m<3=90 : definition of complementary angles

a)statement:m<1=m<2=2(m<3)=180 reason: angle addition

b)statement:m<1+m<3=m<2+m<3 reason:transitive property of equality

c)statement:m<1=m<2 reason : subtraction property of equality

d)statement:m<1+m<2=m<2+m<3 reason:substitution property of equality

e)statement:2(m<1)=m<2=m<2+m<3 reason: substitution property of equality

please help !