Which measurement below has three significant figures? a) 0.018km b)12.02m c)0.2004g d)12,300lbs

None: a has 2 b has 4 c has 4 and d is ambiguous because it doesn't have a decimal.

1. and 2. question: in which equation? or i don't understand you, 3. a), 4. c), 5. c), 6. b), 7. d), 8. d) if small number is underlined(behind symbol) , b) if big number is underlined(in front of symbol)9. what is underlined there? 10. c)