Friday Funny: Solution to Clocks, Calculators and Lightbulbs algebra maths puzzle

A month ago I posted another picture algebra maths puzzles. This time it was the Clocks, Calculators and Lightbulbs algebra maths puzzle which looked simple but had more to it than you would initially think.
[Edit] This puzzle was originally created by Leander from 123 Puzzle Me.
If you have not had a go at solving this puzzle and registering your answer on the poll; Stop reading the solution, click on the link above and go do it now. 🙂
