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

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

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

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

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

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

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

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

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

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

Solving
3k = 63

Solving for variable 'k'.

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

Divide each side by '3'.
k = 21

Simplifying
k = 21