I 'm afraid I don't understand what you're trying to do, mathematically.
Without the variable 'e', you have a system of 3 equations and 2 unknowns which have a single (trivial) solution: {a = 0, x = 0}. You can see this visually in Maple with:
mySystem := {7*a-20*x/(3.14) = 0, 40*a-443*x/(3.14)=0, 105*a-543*x/(3.14) = 0};
plots[implicitplot]( mySystem, x = -5..5, a = -5..5 )
That is, you have three lines with different slopes which coincide at the origin. What other solution were you hoping for?
If you force each equation to be equal to 'e' (the same 'e' in each equation), you're only shifting the solution set. Perhaps what you want to do is specify an overall error tolerance and find a neighbourhood of the solution space in which that tolerance holds? Is that correct.
A couple comments purely about Maple: the tool to use for finding approximate solutions to systems is fsolve, not solve. Also I see 3.14 appearing in your equations: if you mean pi, the Maple name for that is Pi.