Answer: 76%
The fraction of questions Emerson has completed is 19/25. To convert this to a percentage, we want to write this as something divided by 100. To do so, multiply the numerator and denominator by 4, to get the fraction 76/100. Therefore, Emerson has completed 76% of the homework questions.
If you have access to a calculator, a more efficient way to solve such a question would be to convert 19/25 to a decimal (it is equal to 0.76), and multiply by 100 to get 76%.