It's a simple linear equation in 'k' .
If you're ever asked to find the "solution", remember that the solution is
the number that 'k' must be in order to make the equation a true statement.
Since the equation is linear, there's only one possible solution.
Here's a procedure you can use to find the solution.
It's rather complicated. Please try to follow me. I'll go slowly:
-- Write the equation: 1k + 3 = 5k - 3
-- Subtract 1k from each side: 3 = 4k - 3
-- Add 3 to each side: 6 = 4k
-- Divide each side by 4 : 6/4 = k or k = 1.5 (same thing)