From first equation,
3x = 4y-17
x =(4y - 17) / 3 - - - - - - Third equation
Substitute third equation into second equation,
32y / 3 - 136 / 3 - 3y = - 7
23y /33 = 115 / 33
23y = 115
y = 5
Substitute y = 5 into first equation,
3x - 4y =-17
3x - 4(5) = - 17
3x - 20 = - 17
3x = 3
x = 1
Thus, x = 1 and y = 5.