a, $(18×4+6):(18×5-12)$
= $(6×3×4+6):(6×3×5-6×2)$
= $[6×(3×4+1)]:[6×(3×5-2)]$
= $6:6×(3×4+1):(3×5-2)$
= $13:13$
= $1$
b, $(2006×36-2000):(2006×35+6)$
= $(2006×35+2006-2000):(2006×35+6)$
= $(2006×35+6):(2006×35+6)$
= $1$
c, $\frac{35×6-21}{35×5+14}$
= $\frac{35×5+36-21}{35×5+14}$
= $\frac{35×5+14}{35×5+14}$
= $1$
d, $\frac{288×6-88}{288×5+200}$
= $\frac{288×5+288-88}{288×5+200}$
= $\frac{288×5+200}{288×5+200}$
= $1$
