75,78(3,4) please please

Question

75,78(3,4) please please

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Answer 1

77.
1)8.07
2)4,0037
3)0,000475

Answer 2

8,07
4,0037
0,000475
---------------------
    4с
= ----
    9а²

    24d      3
= ------ = ----- = 1 1/2
    16d      2