(16+19 2 per 5):2 19 per 20

( 16 + 19 2/5) : 2 19/20 =
(16 + 19 8/20) : 2 19/20 =
35 8/20 : 2 19/20 =
708/20 : 59/20 =
708/20 × 20/59 = 14160/1180 = 12