sci.op-research

Greetings!

Is there a mathematical software that solves symbolically a parametric
linear program, like that one:

min x + y
subject to ax + y >= 4
bx + y >= 7
x >= 0, y >=0

That is, I would like to see the solution in terms of the coefficients
a and b:

(x*, y*) = (3/(a - b), (4a - 7b)/(a - b)) if 7/a <= 4/b
(x*, y*) = (7/a, 0), otherwise.

Thanks in advance, Humberto.