由方程式化简得 15x*y + 12x*y = 2.7 * [ (3 + 2)* x ]
(15 + 12)*x*y = 2.7 * 5 * x
27* x * y = 2.7 * 5 * x
y = 2.7 * 5 * x /(27 * x)
y = 0.1 * 5
y = 0.5