35/70 = 50%
A fraction like 35/70 often shows up when half of a group, survey, or collection meets a certain condition. For example, if 35 out of 70 students choose one activity, that represents 50% of the students.
You can picture 35/70 quickly as one equal-sized half of a whole. If the top number is about half of the bottom number, you can estimate that the value is close to 50%.
A common point of confusion is thinking that a larger pair of numbers must mean a larger percentage. The numbers 35 and 70 may look different from smaller numbers, but the fraction still describes exactly half.