63=k+(k-r)+2r+(k-r)

Solution for 63=k+(k-r)+2r+(k-r) equation:

Simplifying
63 = k + (k + -1r) + 2r + (k + -1r)

Remove parenthesis around (k + -1r)
63 = k + k + -1r + 2r + (k + -1r)

Remove parenthesis around (k + -1r)
63 = k + k + -1r + 2r + k + -1r

Reorder the terms:
63 = k + k + k + -1r + 2r + -1r

Combine like terms: k + k = 2k
63 = 2k + k + -1r + 2r + -1r

Combine like terms: 2k + k = 3k
63 = 3k + -1r + 2r + -1r

Combine like terms: -1r + 2r = 1r
63 = 3k + 1r + -1r

Combine like terms: 1r + -1r = 0
63 = 3k + 0
63 = 3k

Solving
63 = 3k

Solving for variable 'k'.

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

Add '-3k' to each side of the equation.
63 + -3k = 3k + -3k

Combine like terms: 3k + -3k = 0
63 + -3k = 0

Add '-63' to each side of the equation.
63 + -63 + -3k = 0 + -63

Combine like terms: 63 + -63 = 0
0 + -3k = 0 + -63
-3k = 0 + -63

Combine like terms: 0 + -63 = -63
-3k = -63

Divide each side by '-3'.
k = 21

Simplifying
k = 21