0.2 m+1 1/5dm-25cm=.....mm

0,2 m ( 0,2 × 1.000 = 200 mm )
6/5 dm = 1,2 dm ( 1,2 × 100 = 120 mm )
25 cm = ( 25 × 10 = 250 mm )

200
120
--------- +
320

320
250
---------- -
...70