To add fractions with different denominators, we first need to find a common denominator for all the fractions.

For the first equation:
3.7/9 + 5.1/6

We can find a common denominator by multiplying 9 and 6, which gives us 54.
So, now we can rewrite the fractions with a common denominator:
(3.7 6)/(9 6) + (5.1 9)/(6 9)
= 22.2/54 + 45.9/54
= (22.2 + 45.9)/54
= 68.1/54

For the second equation:
9.3/16 + 4.7/12 + 3.5/24

We can find a common denominator by multiplying 16, 12, and 24, which gives us 384.
So, now we can rewrite the fractions with a common denominator:
(9.3 24)/(16 24) + (4.7 32)/(12 32) + (3.5 16)/(24 16)
= 223.2/384 + 150.4/384 + 56.0/384
= (223.2 + 150.4 + 56.0)/384
= 429.6/384

Therefore, the final result for both equations is:
68.1/54 + 429.6/384