Răspuns:
Explicație pas cu pas:
a/5 = b/12 ; b = 12a/5
b-a = 16 ; b = a+16
a+16 = 12a/5
5a+5*16 = 12a
7a = 5*16 ; a = 5*16/7
b = 12/5 *(5*16/7) ; b = 12*16/7
13b = 12c
12c = 13*12*16/7
c = 13*12*16/(7*12); c = 13*16/7
P = a+b+c =
5*16/7 + 12*16/7 + 13*16/7 =
16(5+12+13)/7 = 16*30/7