To solve these equations, we first simplify the fractions:

1) 8.2/5 - 2.4/9
= (8.2 9)/(5 9) - (2.4 5)/(9 5)
= 73.8/45 - 12/45
= (73.8 - 12)/45
= 61.8/45

2) 2.5 + 7.5/8
= 2.5 + 0.9375
= 3.4375

3) 5.1/4 - 1.2/3
= (5.1 3)/(4 3) - (1.2 4)/(3 4)
= 15.3/12 - 4.8/12
= (15.3 - 4.8)/12
= 10.5/12

Therefore, the solutions are:
1) 61.8/45
2) 3.4375
3) 10.5/12 or 35/4