(3 1/5 + 2 1/4) * 5 - 25 5/6 =

(3 1/5 + 2 1/4 ) * 5 - 25 5/6 = (16/5 + 9/4) * 5 - 155/6 = (16*4/5*4 + 9*5/4*5) * 5 - 155/6 = (64/20 + 45/20) * 5 - 155/6 = 109/20 * 5 - 155/6 = 109*5/20 - 155/6 =
 545/20 - 155/6 = 109/4 - 155/6 = 109*6/4*6 - 155*4/6*4 = 654/24 - 620/24 = 34/24 = 17/12 = 1 5/12

(3 1/5 + 2 1/4) * 5 - 25 5/6 = 1 5/12

1) 3 1/5 + 2 1/4 = 3 4/20 + 2 5/20 = 5 9/20

2) 5 9/20 * 5 = 109/20 * 5 = 545/20 = 27 5/20 = 27 1/4

3) 27 1/4 - 25 5/6 = 27 6/24 - 25 20/24 = 26 30/24 - 25 20/24 = 1 10/24 = 1 5/12