(7 1/8-х)+2 3/8=5 7/8

7 1/8 - x + 2 3/8 = 5 7/8;

x = 7 1/8 + 2 3/8 - 5 7/8;

x = 9 4/8 - 5 7/8;

x = 4 4/8 - 7/8 = 3 5/8;