simplify the following by adding like terms -4-6m+10n-56-n+9m

-4-6m+10n-56-n+9m

-60 + 9n + 3m

To simplify the given expression by adding like terms, we need to combine the terms with the same variables (m and n).

First, let's group the terms with the variable m:
-4 - 6m + 9m.

When we combine -6m and 9m, we add their coefficients:
(-6 + 9)m = 3m.

Next, let's group the terms with the variable n:
10n - n.

When we combine 10n and -n, we also add their coefficients:
(10 - 1)n = 9n.

Now, let's put everything together:

-4 - 6m + 10n - 56 - n + 9m = (-4 - 56) + (3m + 9m) + (10n - n).

Combining the constants:
-60 + (3m + 9m) + (10n - n).

Now, combining the coefficients of m and n respectively:
-60 + 12m + 9n.

Therefore, the simplified expression by adding like terms is:
-60 + 12m + 9n.