4x + 9y = 5
-5x + 3y = 8
2y - (3/x) = 12
5y + (7/x) = 1
(3/x) + (2/y) = (9/xy)
(9/x) + (4/y) = (21/xy)
4/(p - 3) + 6/(q - 4) = 5
5/(p - 3) - 3/(q - 4) = 1
3 - 2(3a - 4b) = -59 (a - 3)/4 - (b - 4)/5 = 2¹/₁₀