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Obtain a particular solution for a system of inequalities whose variables can only take certain values

I want to get a particular solution (assuming it exists) of a system of inequalities, with 4 variables, having that those variables can take only certain values. What I have so far is:

a, b, c, d = var('a', 'b', 'c', 'd')

assume(a >= 1 and a <= 8) assume(b >= 4 and b <= 512) assume(c >= 2 and c <= 128) assume(d, 'integer')

eq1 = (SRC / a) * b <= 418
eq2 = (((SRC / a) * b) / c) / d <= 200
eq3 = ((SRC / a) * b) / c <= 480


res = solve([eq1, eq2, eq3], a, b, c, d=1)

for i in res:
    print(i)

The first result I obtain is:

[a < 0, 0 < c, -d > 0, 25*a*c*d - 8*b > 0, -15*a*c + 2*b > 0]

As you can see, a < 0, but I have stated that a must be greater than 1. Why this happens?

How can I obtain a particular solution (if it exists)?

Obtain a particular solution for a system of inequalities whose variables can only take certain values

I want to get a particular solution (assuming it exists) of a system of inequalities, with 4 variables, having that those variables can take only certain values. What I have so far is:

SRC = 64 a, b, c, d = var('a', 'b', 'c', 'd') 'd') assume(a >= 1 and a <= 8) assume(b >= 4 >=4 and b <= 512) assume(c >= 2 and c <= 128) assume(d, 'integer') 'integer') eq1 = (SRC / a) * b <= 418 eq2 = (((SRC / a) * b) / c) / d <= 200 eq3 = ((SRC / a) * b) / c <= 480 res = solve([eq1, eq2, eq3], a, b, c, d=1) for i in res: print(i) The first result I obtain is: [a < 0, 0 < c, -d > 0, 25*a*c*d - 8*b > 0, -15*a*c + 2*b > 0] As you can see, a < 0, but I have stated that a must be greater than 1. Why this happens? How can I obtain a particular solution (if it exists)?