There is a total of 53 Yr 11 students. 18 in math 13 in science making 31 students, leaving 22 Year 11 students for english. 37 total students picked english, so that makes 15 the remaning amount which is put into the Yr12 students.
There are 100 students total. 53 of which are Yr 11 students leaving 47 to be Yr12 students.
12 Yr 12 students chose science, 15 Yr 12 kids chose english, leaving 20 Yr12 students to have chosen math.
12+15+20=47 Yr 12 students.
22+18+13=52 Yr 11 students.
15 Yr 12 students chose english.
20 Yr 12 students chose math.
12 Yr 12 students chose science.
There are 47 Yr 12 students total.
22 Yr 11 students chose english.
18 Yr 11 students chose math.
13 Yr 11 students chose science.
There are 53 Yr 11 students.