Răspuns :
a - b = 15
a : b = 4 l = > a = 4b
4b - b = 15
3b = 15
b = 5
a = 20
2 ( a + b ) = 2 × 25 = 50
a : b = 4 l = > a = 4b
4b - b = 15
3b = 15
b = 5
a = 20
2 ( a + b ) = 2 × 25 = 50