1.19/56+47/70=133/70+376/70=509/70=719/70
2. 16/45+43/99=176/99+215/99=391/99=
= 3 84/99
3. 35/63+81/98=490/98+729/98=1219/98=
=12 43/98
4. 61/81-35/72=488/81-315/81= 173/81= 2 11/81
5. 87/128-91/160=2784/320-1820/320=
=964/320= 3 3/320
6. 141/270-102/210=987/270-102/270=
=885/270=3 175/270= 3 35/54.