1. a, b, c = numere
a + b + c = 450
a = 2b
b - c = 50 => b = c + 50
2b + b + c = 450
3b + c = 450
3 x (c + 50) + c = 450
3c + 150 + c = 450
4c + 150 = 450
4c = 450 - 150
4c = 300
c = 300 : 4
c = 75 => b = 75 + 50
b = 125 => a = 2 x 125
a = 250
La a doua sincer ma cam incurc in cifre, ca sunt prea obosita... Scuze!:*