Notam: p = Paul m = Maria g= George b= bunica
p = m +3 (1)
g = m -5 (2)
b = 3 (p +m + g) (3)
p + m + g + b =100
inlocuim (1), (2) si (3) si obtinem:
m+ 3 + m + m- 5 + 3 (m + 3 + m + m-5) = 100
m +3 +m +m-5 + 3m +9 +3m +3m- 15 = 100
12 m -8 = 100
12m = 108
m= 9 (Maria are 9 ani)
p = 9 +3
p = 12 (Paul are 12 ani)
g = 9-5
g = 4 (George are 4 ani)
b = (9 +12+ 4)*3
b = 25 *3
b = 75 (bunica are 75 ani)
verificare 9 +12 +4 +75 = 100