Hi Cosma,
Here is one way (not saying it's the only one :)
First step: get all multiples of 2 to the same high denominator:
x/6 + x/12 + x/7 + 5 + x/2 + 4 = x <=> 2x/12 + x/12 + x/7 + 5 + 6x/12 + 4 = x
Then you add them up:
2x/12 + x/12 + x/7 + 5 + 6x/12 + 4 = x <=> 9x/12 + x/7 + 9 = x
And actually your equation is equivalent to 3x/4 + x/7 + 9 = x
Then you bring it all to the same denominator which gives you 21x/28 + 4x/28 + 9 = x
And finally you have 9 = 3x/28 which is equivalent to x = 28*3 = 84
Hope this helps :)
