P4 Math Question - Equal Stage

In a class, 1/4 of the students are boys. After 3/5 of the boys and 2/5 of the girls left the class, there were 154 students that remained. Find the total number of students in the class at first.

Answer - using models:

 Make the units the same size:

 Number of remaining units = 11:

P4 Math Question - Equal Stage

At the school hall, there were 30 less boys than girls. After 3/5 of the boys and 5/8 of the girls had left the hall for recess, there was an equal number of boys and girls remaining. Find the number of boys who were in the school hall at first.

Answer using model: