30x⁴y⁸ 6 x²y
------------ = ----------
55x²y⁷z 11z
4a(a-1) 1
--------------- = --------
8a²b(a-1) 2ab
c²+cd c(c+d) c
------------- = ----------- = --------
8c+8d 8(c+d) 8
14t-21z 7(2t-3z) 7
---------------- = --------------------- = --------------
4t²-9z² (2t-3z)(2t+3z) 2t+3z
m²-4m+4 (m-2)² m-2
-------------------- = ----------------- = -------------
m²-2m m(m-2) m
2x-4 2(x-2) 2
------------ = ----------------------- = ------------------
x³-8 (x-2)(x²+2x+4) (x²+2x+4)