9. Efectuați: a) (5/8 + 1/4) ×12=
b) (4/15 - 1/5) × 25 =
c) (3/4 - 7/12) ×9 =
d) (7/15 + 1/5)×3 =
e) (3/7 - 1/21) ×14=
f) (1 - 1/9) × 3 =​