a)

200 mm + 100 mm = 300 mm

200 mm x 3 = 600 mm

600 mm : 3 = 200 mm

b) 300 g + 200 g = 500 g

200g x 5 = 1 000g

500g – 300g = 200g

1 000g : 5 = 200g

c)

400 ml + 300 ml = 700 ml

800 ml : 4 = 200 ml

700 ml – 300 ml = 400 ml

200 ml x 4 = 800ml.