3y-4x=29, 2y+5x=4. Multiply the first equation by 5 and the second by 4:
15y-20x=145, 8y+20x=16, now add them together:
23y=161, y=161/23=7. Substitute for y in either original equation:
21-4x=29, -8=4x, x=-2.
14+5x=4, 5x=-10, x=-2.
Solution: x=-2, y=7.