Answer:
34
Explanation:

Long way
- multiply the two numerators
- multiply the two denominators
- simplify the new fractions

short way
-can be simplified before mulitplying
- factor out common factors in the numerator and denominator

Think 85 and 5 as nickels. You need 20 nickels to make 100. Subtract 100 by 85 to get 15. You get 3 nickels and 17 nickels. 17 is the common factor. Multiply 17 by 2 to get your answer.