1/5 of the people in a park were men. 3/4 of the remainder were women and the rest were children. There were 60 children in the park. How many people were there in the park?

men: 1/5, leaving 4/5

women: 3/4 * 4/5 = 3/5, leaving 1/5
so, now you know that if there are x people in the park,
1/5 x = 60
x = 300