42=2(l+w)

Solution for 42=2(l+w) equation:

Simplifying
42 = 2(l + w)
42 = (l * 2 + w * 2)
42 = (2l + 2w)

Solving
42 = 2l + 2w

Solving for variable 'l'.

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

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

Combine like terms: 2l + -2l = 0
42 + -2l = 0 + 2w
42 + -2l = 2w

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

Combine like terms: 42 + -42 = 0
0 + -2l = -42 + 2w
-2l = -42 + 2w

Divide each side by '-2'.
l = 21 + -1w

Simplifying
l = 21 + -1w