ab + a + 2b + 2 = (a + 2) (b + 1) = 32
① (a + 2) (2b + 2) = 64
所以：
64 = (a + 2) (2b + 2)
= 16-4 = 12
而(a + 2b) + ab = 30
所以：ab = 30 - (a+2b)