In the science club, 1/2 the students are freshman, 1/20 are sophomores, 1/10 are juniors, and 70 students are seniors. How many students are sophomores?

So we are using the denominator 20.

1/2 of 20 would be 10.

So, out of 20 we multiply it by 10 since it is our numerator.

Now, we have converted it to 100/200.

Freshman : 100 students

Sophomores : 10 students

Juniors : 20 students

Seniors : 70 students