Theorem leadd1i

Description: Addition to both sides of 'less than or equal to'. (Contributed by NM, 11-Aug-1999)

	Ref	Expression
Hypotheses	lt2.1	$$⊢A\in ℝ$$
	lt2.2	$$⊢B\in ℝ$$
	lt2.3	$$⊢C\in ℝ$$
Assertion	leadd1i	$$⊢A\le B\leftrightarrow A+C\le B+C$$

Proof

Step	Hyp	Ref	Expression
1		lt2.1	$$⊢A\in ℝ$$
2		lt2.2	$$⊢B\in ℝ$$
3		lt2.3	$$⊢C\in ℝ$$
4		leadd1	$$⊢\left(A\in ℝ\wedge B\in ℝ\wedge C\in ℝ\right)\to \left(A\le B\leftrightarrow A+C\le B+C\right)$$
5	1 2 3 4	mp3an	$$⊢A\le B\leftrightarrow A+C\le B+C$$