Abigail is 8 years older than cynthia. twenty years ago abigail was three times as old as cynthia. how old is each now?

Let 
C=Cynthia's age today
A=Abigail's age today

then
at all times
A=C+8(1)
twenty years ago,
A-20=3(C-20)
simplifying
A=3C-40(2)

Equate (1) and (2),
C+8=3C-40
8+40=3C-C
C=24
=> 
A=32

Check:  A-C=8... ok   A-20=12  C-20=4  => (A-20)=3(C-20) ...ok

Abigail is 32, Cynthia is 24.