you got 85% of the questions on the test correct, this means if the total amount of questions was 100, you got 85 of them correct
So the fraction is 85/100
and to write it in lowest terms we can divide each term by 5:
[tex]\frac{\frac{85}{5}}{\frac{100}{5}}=\frac{17}{20}[/tex]So the answer is: 17/20