8.300 cm - 650 dm + 12 dam =...... m

8.300 cm = 83 m
650 dm = 65 m
12 dam = 120 m

83 - 65 + 120 = 138 m

= 8.300 cm - 650 dm + 12 dam
= (8.300/100) m - (650/10) m + (12x 10) m
= 83 m - 65 m + 120 m
= 138 m