78=-2(m+3)+n

Solution for 78=-2(m+3)+n equation:

Simplifying
78 = -2(m + 3) + n

Reorder the terms:
78 = -2(3 + m) + n
78 = (3 * -2 + m * -2) + n
78 = (-6 + -2m) + n

Solving
78 = -6 + -2m + n

Solving for variable 'm'.

Move all terms containing m to the left, all other terms to the right.

Add '2m' to each side of the equation.
78 + 2m = -6 + -2m + 2m + n

Combine like terms: -2m + 2m = 0
78 + 2m = -6 + 0 + n
78 + 2m = -6 + n

Add '-78' to each side of the equation.
78 + -78 + 2m = -6 + -78 + n

Combine like terms: 78 + -78 = 0
0 + 2m = -6 + -78 + n
2m = -6 + -78 + n

Combine like terms: -6 + -78 = -84
2m = -84 + n

Divide each side by '2'.
m = -42 + 0.5n

Simplifying
m = -42 + 0.5n