Answer: 39/50
Step-by-step explanation: Using the place value chart, we can recognize that 0.78 means seventy-eight hundredths which can be written as the fraction 78/100.
Notice however that 78/100 is not in lowest terms so we need to divide the numerator and the denominator by 2 to get 39/50.
So 0.78 can be written as 39/50.
Image is attached showing the place value chart.
