Answer:
642 mm or 64.2 cm
Step-by-step explanation:
67cm-28mm
We need the same units
67 cm * 10 = 670 mm
670 mm - 28 mm
642 mm
We can convert back to cm by dividing by 10
64.2 cm
642mm or 64.2 cm
67 cm = 670mm
So, that's 670-28mm = 642mm
