Question 174426
Usually, in order to be solvable, the number of equations
has to equal (or be greater than) the number of unknowns
You have 3 equations and 4 unknowns
{{{c = x + 8}}}
{{{b = x}}}
{{{a = x + 7}}}
As written, there is no way to solve this
Suppose I say {{{x = 5}}}, then
{{{c = 5 + 8}}}
{{{b = 5}}}
{{{a = 5 + 7}}}
{{{c=13}}},{{{b=5}}},and{{{a=12}}}
But suppose I say {{{x = 11}}}, then
{{{c = 11 + 8}}}
{{{b = 11}}}
{{{a = 11 + 7}}}
The point is, there is no single value of {{{x}}} that makes
the solution the one and only correct one. 
Any {{{x}}} that you pick will make a solution