d) [ 25 ( 36x - 11x)] : 125 = 500
( 25 · 25x) : 125 = 500
625x : 125 = 500
5x = 500
atunci x = 500:5
atunci x = 100 ∈ N
e) ( 12x) : 4 = 30
3x = 30
atunci x = 30:3
atunci x = 10 ∈ N
f) ( 3x + 7x) : 2 = 15
10x : 2 = 15
5x = 15
atunci x = 15:5
atunci x = 3 ∈N