Add :
5m – 7n, 3n – 4m + 2, 2m – 3mn – 5...........

Dear Student

When term have the same algebraic factors, they are like terms.
Then, we have to add the like terms
= 5m–7n + (3n–4m + 2) + (2m–3mn - 5)
= 5m–7n + 3n–4m + 2 + 2m–3mn–5
= 5m–4m + 2m–7n + 3n–3mn + 2–5
= m (5 - 4 + 2) + n (-7 + 3)–3mn + (2 - 5)
= m (3) + n (-4)–3mn + (-3)
= 3m–4n–3mn - 3
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Thanks