( 2 3/5 - 5/8 ) : 19 3/4 = 0.1

1) 2 3/5 - 5/8 = 2 24/40 - 25/40 = 1 64/40 - 25/40 = 1 39/40 = 1.975

2) 1 39/40 : 19 3/4 = 79/40 : 19/4 = 79/40 * 4/19 = 1/10 = 0.1