42=-2d

Solution for 42=-2d equation:

Simplifying
42 = -2d

Solving
42 = -2d

Solving for variable 'd'.

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

Add '2d' to each side of the equation.
42 + 2d = -2d + 2d

Combine like terms: -2d + 2d = 0
42 + 2d = 0

Add '-42' to each side of the equation.
42 + -42 + 2d = 0 + -42

Combine like terms: 42 + -42 = 0
0 + 2d = 0 + -42
2d = 0 + -42

Combine like terms: 0 + -42 = -42
2d = -42

Divide each side by '2'.
d = -21

Simplifying
d = -21