Holly finds that (11m - 13n + 6mn) - (10m - 7n + 3mn) = m - 20n + 9mn. What error did Holly make?

Answer: A) She only used the additive inverse of 10m when combining like terms.

Step-by-step explanation:

Holly only used the additive inverse of 10m when combining like terms. The equality is erroneous because the equation was evaluated well. The calculations should be as follows:

11m - 13n + 6mn - 10m + 7n - 3mn = 1m - 6n + 3mn

She should have subtracted 13n and 7n then take the negative value. Also, subtract 6mn and 3mn.

she added 11 plus 10 wrong

Step-by-step explanation:

11 plus 10 = 21