There are several ways and here's one, with a lot of detail that can generally be taken for granted:
2.3 = 3.0 - 0.7 = 3 - 0.7
so
20 - 2.3 = 20 - (3 - 0.7) = 20 - 3 + 0.7 = 17 + 0.7 = 17.7 .. .. .. .. .. (*)
So
2.3 - 20 = -(20 - 2.3) = -(*) = -17.7
P=5.75. You know 4P is 23 because you subtract 3 from it and are left with 20. Just divide 23 by 4 to get the value of each "p".
23
8
Subtract a negative 1. 19 - (-1) = 20
7
20
P=5.75. You know 4P is 23 because you subtract 3 from it and are left with 20. Just divide 23 by 4 to get the value of each "p".
82 subtract by 20 = 62
64
9/23 - 5/23 = 4/23.
8
23
Subtract a negative 1. 19 - (-1) = 20
23
7
20
-23