Students go to the movies. In the first grade, I went to 6 groups with 7 people in each group. 45 people are in the second grade. How many people are in the first grade? How many more people are in Grade Two than in Grade One?

There are 42 students in Class One, 38 students in Class Two and 39 students in Class Three in Grade Two of Bailou Primary School. How many people are there in Class One, Grade Two and Class Two, Grade Two? How many people are there in Class 3, Grade 2 than Class 1, Grade 2?

There are eight willows planted in the green belt. The number of pine trees is three times that of willow trees, and the number of willow trees is four times that of poplar trees. How many pine trees are there in the green belt? How many poplars are there?