a = -Coe.coe n : Prop
a = -Coe.coe n : Prop
-Coe.coe n = a : Prop
-Coe.coe n = a : Prop
a = Coe.coe n + Coe.coe n : Prop
a = Coe.coe n + Coe.coe n : Prop
a = 0 - Coe.coe n : Prop
a = 0 - Coe.coe n : Prop
a + -Coe.coe n : R
a + -Coe.coe n : R
-Coe.coe n + a : R
-Coe.coe n + a : R