0.8m+8.4(m-5.1)=-142.2

Solution for 0.8m+8.4(m-5.1)=-142.2 equation:

Simplifying
0.8m + 8.4(m + -5.1) = -142.2

Reorder the terms:
0.8m + 8.4(-5.1 + m) = -142.2
0.8m + (-5.1 * 8.4 + m * 8.4) = -142.2
0.8m + (-42.84 + 8.4m) = -142.2

Reorder the terms:
-42.84 + 0.8m + 8.4m = -142.2

Combine like terms: 0.8m + 8.4m = 9.2m
-42.84 + 9.2m = -142.2

Solving
-42.84 + 9.2m = -142.2

Solving for variable 'm'.

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

Add '42.84' to each side of the equation.
-42.84 + 42.84 + 9.2m = -142.2 + 42.84

Combine like terms: -42.84 + 42.84 = 0.00
0.00 + 9.2m = -142.2 + 42.84
9.2m = -142.2 + 42.84

Combine like terms: -142.2 + 42.84 = -99.36
9.2m = -99.36

Divide each side by '9.2'.
m = -10.8

Simplifying
m = -10.8