b) 5x + 9y = -6
4x - 3y = -15 inmultim relatia cu 3
12x - 9y = -45
adunam cele 2 relatii
17x = -51 ==> x = -3
-15 + 9y = -6 ==> 9y = 9 ==> y = 1
17) b)
5x - 3y = 19 inmultim relatia cu 4
9x + 4y - 6 = 0 ==> 9x + 4y = 6 inmultim relatia cu 3
20x - 12y = 76
27x + 12y = 18
adunam relatiile
47x = 94 ==> x = 2
10 - 3y = 19 ==> 3y = -9 ==> y = -3
