a. proprietatea fundamentala a proportiei
11x=12y inlocuim 11x in inecuatie
12y-9y≤8
3y≤8
y≤8/3, y∈N*⇒ y∈{1,2}
y=1, 11x=12, x=12/11 ∉N*
y=2, 11x=24, x=24/11 ∉N*
deci S=∅ (nu avem solutii naturale)
b. 4x=3y
4·4x-7y≤20
12y-7y≤20 |:4
5y≤5
y≤1, y∈N*⇒y∈{1}
y=1, 4x=3, x=3/4∉N*
S=∅
