posted by mel on .
Please help me with this. I just don't get it.
The average rate of chemical weathering of carbonate rock in an urban area is 2.1 x 10^-3 mm/yr. The depth of lettering of the tombstones shown in the table below was measured in 2010:
Date on Tombstone Age (yr)
How much has the depth of the lettering been reduced on each tombstone?