Explicație pas cu pas:
a
72/60=12/10=6/5
b
66/880=33/440=3/40
c
10a+b+10b+a/10x+y+10y+x
11a+11b/11x+11y
11(a+b)/11(x+y)
a+b/x+y
d
10a+3+30+a/70+a+10a+7
11a+33/11a+77
11(a+3)/11(a+7)
a+3/a+7
