Răspuns :
( a + b ) × 2 = 60
a + b = 60 : 2
a + b = 30
a = b : 2
b : 2 + b = 30 | × 2
b + 2 × b = 60
3 × b = 60
b = 60 : 3
b = 20
a = 20 : 2
a = 10
a + b = 60 : 2
a + b = 30
a = b : 2
b : 2 + b = 30 | × 2
b + 2 × b = 60
3 × b = 60
b = 60 : 3
b = 20
a = 20 : 2
a = 10