Measured distance: 84ft
actual distance: 80ft
percent error: ?

1. Subtract the actual distance from the measured distance to find the error:
                80-84= -4 (just ignore the negative sign) so our error is 4
2. Divide error by the actual distance:
                4/80= 0.05
3. Multiply that by 100 to find percent:
               .05*100= 5%
Percentage error is 5%