Szczegółowe wyjaśnienie:
a) 30/55 = 6/11
b) -(4/27)
c) 28/72 = 7/18
d) -20/90 = -2/9
e) -(8/28) = -2/7
f) -(144/24) = -(36/4) = -9
g,) 42/240 = 21/120 = 7/40
h) -63/42 = -1 21/42 = -1½
sorka za ewentualne błędy ;))