To find the combined unit rate of painting the fence, we need to add up the rates at which Amy and Bob can paint the fence individually.
Amy can paint the fence at a rate of 5 square meters per hour, and Bob can paint the fence at a rate of 8 square meters per hour.
When they work together, their combined unit rate is the sum of their individual rates. So, the combined unit rate of painting the fence is 5 + 8 = 13 square meters per hour.
