I read this as: (y-6x+51)/(1+7x-(9/72))=x. If we need to solve for y, x needs to be treated like a constant. The trouble is that, in the absence of brackets, this question can be interpreted in different ways, so my interpretation may differ from the questioner's intention. One thing's for certain: with one equation we can only solve for x or y, not both, and the indication is to solve for y and leave x as an unknown value.
The denominator looks like it can be simplified: 9/72=1/8 and this can be combined with 1: 1-1/8=7/8. The denominator could be written: 7(1/8+x). Multiply through by this denominator: y-6x+51=7x(x+1/8), so y=6x-51+7x^2+7x/8⇒y=7x^2+55x/8+51=(56x^2+55x+408)/8. The quadratic doesn't factorise (its zeroes are complex), so that looks like the best we can get out of this interpretation.
Another interpretation is: y-(6x+51)/(1+7x)-9/72=x; y-3(2x+17)/(1+7x)-1/8=x.
Multiply through by 8(1+7x): 8y(1+7x)-24(2x+17)-(1+7x)=8x(1+7x).
8y(1+7x)=48x+408+1+7x+8x+56x^2=56x^2+63x+409, so y=(56x^2+63x+409)/8(7x+1).
Perhaps the reason for lack of response is the ambiguity of the question.