Answer: 4/5
Step-by-step explanation: To write a percent as a fraction in lowest terms, first remember that a percent is a ratio that compares a number to 100. In this case, 80% can be written as the ratio 80 to 100 of 80/100. Notice however that 80/100 is not in lowest terms so we need to divide both the numerator and denominator by the greatest common factor of 80 and 100 which is 20.
80 ÷ 20 = 4
100 ÷ 20 = 5
Therefore, 80% can be written as the fraction 4/5 which is in lowest terms.