3/4 * 1 1/15 + 1 1/15 * 2 1/2 - 1 3/8 * 1 1/15 =

= 1 1/15 * (3/4 + 2 1/2 - 1 3/8) =

= 1 1/15 * (6/8 + 2 4/8 - 1 3/8) =

= 16/15 * (2 10/8 - 1 3/8) =

= 16/15 * 1 7/8 = 16/15 * 15/8 = 2