Răspuns:
Explicație pas cu pas:
a)
a + b = 30
a/b = 3/7
a = 3b/7
3b/7 + b = 30
3b/7 + 7b/7 = 30
10b/7 = 30
b = 30*7/10 = 21
a = 30 - 21 = 9
b)
aici poti avea doua cazuri
a - b = 12
3b/7 - b = 12
3b/7 - 7b/7 = 12
-4b/7 = 12
b = -12*7/4 = -21
a = 12 + b = 12 - 21 = -9
sau
b - a = 12
b - 3b/7 = 12
7b/7 - 3b/7 = 12
4b/7 = 12
b = 7*12/4 = 21
a = 3*21/7 = 9
