Some figures are arranged in the order of □ □ □ 0000 △ □ □ □ 0000 △ Answer with marks

Some figures are arranged in the order of □ □ □ 0000 △ □ □ □ 0000 △ Answer with marks

The 78th row is △ so it should be 1 / 3

There are seven black pieces and five white pieces on the chessboard. Take one of the black pieces, and the black pieces account for several parts of the total number

6 out of 11

For talent performance, there are several first, second and third prizes. One half of the winners are first and second prizes. The second and third prizes account for 4 / 5 of the total winners
How many of the first, second and third prizes account for the total number of winners

1 / 2 + 5 / 4 = 7 / 4
Second prize: 7 out of 4 minus 1 = 3 out of 4
First prize: 1 / 2 minus 3 / 4 = 1 / 4
Third prize: 4 out of 5 minus 1 out of 4 = 9 out of 20
A: 3 / 4 of the second prize, 1 / 4 of the first prize and 9 / 20 of the third prize