Newbie question re: finding an equation for a set of known variables?



Rather than solving an equation for a variable(s), I'm wondering if it's 
possible to find (simple) equations provided all of the variable values? 
  For example, given the values:

a=5, b=3, c=1, d=7
a=10, b=5, c=2, d=13

where the variables provided are identified as either LHS (a, b, c) or 
RHS (d) for Maxima to determine the equation that fits the variables. 
In this example the result I would be looking for is a+b-c=d.

Thanks,
Phil