HARD SUBTRACTION. Be able to answer this in less than one minute.

1.99 10 =   26.81 26 =
2.79 18 =   27.78 27 =
3.42 25 =   28.69 22 =
4.70 70 =   29.94 89 =
5.33 24 =   30.98 16 =
6.69 33 =   31.64 17 =
7.44 23 =   32.47 33 =
8.64 47 =   33.66 46 =
9.52 34 =   34.85 17 =
10.98 97 =   35.83 70 =
11.40 33 =   36.45 37 =
12.64 48 =   37.83 80 =
13.66 16 =   38.73 55 =
14.70 13 =   39.89 40 =
15.50 29 =   40.92 91 =
16.71 68 =   41.62 16 =
17.65 45 =   42.80 45 =
18.54 10 =   43.87 62 =
19.71 40 =   44.29 15 =
20.81 28 =   45.59 56 =
21.39 18 =   46.98 16 =
22.83 77 =   47.67 28 =
23.58 16 =   48.85 31 =
24.50 43 =   49.76 15 =
25.70 49 =   50.92 14 =