1) 2x - 5y = 4
2) 3x + 4y = 9
multiply eq(1) by 3 and eq(2) by -2, add:
6x - 15y = 12
-6x - 8y = -18
_____________
- 23y = -6
y = 6/23
using eq(1):
2x - 5(6/23) = 4
2x - 30/23 = 4
2x = 4 + 30/23 = 92/23 + 30/23 = 122/23
x = 61/23
check using eq(2):
3(61/23) + 4(6/23) = 9
183/23 + 24/23 = 9
9 = 9
x = 61/23, y = 6/23